超星Medical Statistics课后答案(学习通2023完整答案)

Chapter1 Introduction and Basic Concepts

Introduction and Basic Concepts

1、超星Which one of the following symbols could represent a population parameter?后答
A、?案学
B、x
C、习通p
D、完整π
E、答案S

2、超星Which of the following statements about probability is 后答WRONG?
A、Probability is 案学the measure of the likelihood that an event will occur.
B、The习通 value of a probability lies in the interval of [0,1].
C、The完整 frequency of an event E is exactly the probability of the event E.
D、An event with probability of 0 is 答案called an impossible event.
E、In reality,超星 probability is difficult to obtain.

3、To know the average level of lung capacity of Grade 2015 students at the Sun Yat-sen University,后答 an investigator measured the lung capacity of students in 30 sampled classes of Grade 2015 from this University. The whole collection of the measured lung capacity data is a .
A、sample
B、案学population
C、variable
D、statistic
E、parameter

4、A Statistic is
A、equal to a parameter of the population.
B、an exact characteristic of the population.
C、an index calculated based on all data of the population.
D、obtained after studying all the individuals in the population.
E、calculated based on a sample.

5、To make a statistical inference for the population from a sample, the sample should be:
A、the most typical part of the population.
B、any part of the population.
C、the most meaningful part of the population.
D、the most explicit part of the population.
E、a part randomly selected from the population.

Chapter2 Descriptive Statistics

Descriptive Statistics

1、The Statistic in Statistics is: ?
A、obtained from the data of the population.
B、reflection of the statistical characteristics of the population.r
C、an index calculated based on all data of the population.
D、obtained after studying all the individuals in the population.
E、a statistical indicator calculated based on the sample.

2、A researcher measured 50 patients’ weights. There were 13 patients less than 50Kg, and 17 patients over 70Kg, with the rest weighing between 50 and 70Kg. Which type of variable is used by the researcher?
A、quantitative variable
B、categorized variable
C、ordinal variable
D、binary variable
E、nominal variable

3、The conversion of variables can only be done from quantitative variables → nominal variables → ordinal variables →binary variables, which cannot be converted in an opposite direction.

4、The unit of the coefficient of variation is the same as the unit of the original variable.

Descriptive Statistics

1、

Chapter 3 Probability and Distribution

Probability and Distribution

1、Which of the following conditions could make the binomial distribution B(n, π) approximate the Poisson distribution?
A、When n is large and π approaches to 0.
B、When n?￥ .
C、When nπ or n(1-π) approaches to 0.5.
D、When n is large and π approaches to 0.5.
E、When π approaches to 0.5.

2、A certain measurement index shows a logarithmic normal distribution, which is considered as abnormal if it is too high, and which of the following should be used to calculate the range of medical reference value with a scope of 95%？
A、
B、
C、
D、
E、

3、Which of the following statements about the probability is WRONG?
A、Probability is the measure of the likelihood that an event will occur.
B、Any probability takes value from the interval [0,1].
C、The frequency of an event E is exactly the probability of the event E.
D、The event with probability of 0 is called an impossible event.
E、In practice, the probability is difficult to be obtained.

4、Whenλ is large enough, Poisson distribution tends to be a normal distribution.

5、For data subject to a normal distribution, the probability of a variable between 1.96 and 1.96 is 0.95.

Probability and Distribution

1、Please list the main differences among Poisson distribution，binomial distribution and normal distribution?

2、The measured values of total cholesterol in 144 normal adult males aged 30 to 45 years in a certain area approximately followed a normal distribution with a mean of 4.95 mmol/L and a standard deviation of 0.85 mmol/L. （1）Try to estimate the 95% reference value range of total cholesterol for adult males aged 30 to 45 years in this area; （2）What percentage of normal adult males with total cholesterol greater than 5.72mmol/L accounted for?

3、Please list the main difference between reference range and confidence interval?

Chapter 4 Sampling Error and Confidence Interval

Confidence Interval

1、If a t-test shows the difference between two sample means is statistically significant (P<0.05), then confidence interval of the difference between the two population means may not be
A、(1.33, 2.59)
B、(-1.15, 6.08)
C、(-2.33, -1.00)
D、(10, 15)
E、(10, 15)

2、Which of the following statements correctly explains the meaning of the interval .
A、There is a 99% probability that the population mean falls within this interval.
B、There is a 99% probability that the sample mean falls within this interval.
C、It is the 99% confidence interval for the population mean.
D、It is the 99% confidence interval for sample mean.
E、There is a 95% probability that the population mean falls within this interval.

3、Which of the following formulas can be used to estimate the 95% confidence interval for the population mean of a normal distribution_____
A、
B、
C、
D、
E、

4、For a group of given data, the relationship between 95% CI and 99% CI is that
A、99% CI is narrower than 95% CI.
B、95% CI is narrower than 99% CI.
C、95% CI is equal to 99% CI.
D、95% CI is always 1.96 times narrower than 99% CI.
E、99% CI is always 1.96 times narrower than 95% CI.

5、When we intend to estimate the sample size for confidence interval of a population mean which follows a normal distribution, which of the following condition requires a larger sample size while other background remains the same? _____
A、High confidence level
B、Small variation of the individuals
C、Poor precision
D、p is near to 1
E、p is near to zero

Confidence Interval

1、When doing interval estimation for a population mean，how could we decrease the error of confidence interval?

2、How do we distinguish the standard error and the standard deviation?

3、One sample (n=100) is obtained from a population of children, the arithmetic mean of cholesterol is 207.5mg/dl, the standard deviation is 30mg/dl. (1) How to measure the sampling error of the average of the total cholesterol samples of these 100 children? (2)What is the 95% confidence interval of the average cholesterol level of 100 children? (3)What is the 99% confidence interval of the average cholesterol level of 100 children? (4) Why the interval with 99% confidence level is wider than the interval with 95% confidence level?

Chapter 5 Hypothesis Testing for Continuous Variables

Hypothesis testing

1、In hypothesis testing of two groups, which of the following is a null hypothesis?
A、The two population means are different.
B、The two sample means are different.
C、The two population means are the same
D、The two sample means are the same
E、The two sample medians are different

2、Which of the following is NOT a step of hypothesis testing?
A、Set up the hypothesis.
B、Describe the sample information.
C、Select statistics and calculate current value.
D、Decided the P value.
E、Decision and conclusion.

3、Which one of the following statements about P is correct?
A、P value is the probability of the event that the current situation and even more extreme situation based on the assumption that null hypothesis is satisfied.
B、P value is the probability that we reject H1.
C、P value is the probability that we reject H0.
D、P value is defined in advance.
E、P<0.05 means we cannot reject H0.

4、When comparing the effect of two drugs, under which situation one-side test can be used?
A、We know both two drugs are effective.
B、We do not know which one is better.
C、We know drug A is similar to drug B.
D、We do not know if two drugs both are effective.
E、We are sure drug A won’t be better than drug B .

5、Which of the following is NOT a precondition of two independent sample t test?
A、Individuals are randomly selected.
B、The two groups are independent.
C、The two population means are different.
D、The two population variances are the same.
E、The two populations both follow normal distributions.

Hypothesis testing

1、A total of 24 volunteers were recruited into a research project which was to reduce cholesterol. They were completely randomly divided into two groups with 12 individuals for each. Group A received a special diet and group B received a medical therapy. The cholesterol (mmol/L) of each individual was measured before and after the study. The data were showed as the follows: Table 2 The cholesterol (mmol/L) records before and after the study Group A Group B No. Pre-study Post-study No. Pre-study Post-study 1 6.11 6.00 1 6.90 6.93 2 6.81 6.83 2 6.40 6.35 3 6.48 6.49 3 6.48 6.41 4 7.59 7.28 4 7.00 7.10 5 6.42 6.30 5 6.53 6.41 6 6.94 6.64 6 6.70 6.68 7 9.17 8.42 7 9.10 9.05 8 7.33 7.00 8 7.31 6.83 9 6.94 6.58 9 6.96 6.91 10 7.67 7.22 10 6.81 6.73 11 8.15 6.57 11 8.16 7.65 12 6.60 6.17 12 6.98 6.52 questions: (1) Please judge whether the pre-study cholesterol level for the two treatments are equal on average (assume data follow normal distributions). (2) Please judge whether the two treatments are effective on average respectively (assume data follow a normal distribution). (3) Please judge whether the effects on reducing cholesterol are equal on average (assume data follow normal distributions).

Chapter 6 Analysis of Variance

Analysis of Variance

1、Which of the following is NOT a necessary pre-conditions of the Analysis of Variance (ANOVA)?
A、The samples are independent.
B、The variances of the populations are the same.
C、The populations are normally distributed .
D、The means of the populations are not same in all.
E、The samples are randomly selected.

2、The term ‘variance’ of the method ‘Analysis of Variance’ means: .
A、The method is to compare the difference of population variances
B、The method is to compare the difference of sample variances
C、The method requires that variances of different groups should be equal
D、The method calculates MS and compares MS, while MS is variance in concept
E、The method calculates SS and compares SS, while SS is variance in concept

3、Among the following statements about ANOVA, which one is correct？
A、F value can be negative.
B、F value is always larger than 1.
C、MSB can be smaller than MSE.
D、MSB cannot be smaller than MSE
E、SSB cannot be smaller than SSE

4、Which of the following methods CANNOT be used to compare means?
A、One sample t test
B、One-way ANOVA
C、Two-way ANOVA
D、SNK-q test
E、Wilcoxon rank sum test

5、In a randomized block design, 80 individuals were paired into 20 pairs according to similar age, gender and weight, with 4 individuals in each pair. The 4 individuals of each pair were randomly allocated into four groups. The group means were compared. In this study, which of the following is correct?
A、νT = 79
B、νblock = 20
C、νtreatment = 4
D、νtreatment = 19
E、νblock = 3

Analysis of Variance

1、The concentration of chloride(mg/L) of water from a certain lake was measured in different seasons. Does the concentration of chloride vary across the four seasons? Table 1. The concentration of chloride(mg/L) of certain lake water Spring Summer Autumn Winter 22.60 19.10 18.90 19.00 22.80 22.80 13.60 16.90 21.00 24.50 17.20 17.60 17.90 18.00 15.10 14.80 20.00 15.20 16.60 13.10 21.90 18.40 14.20 16.90 21.50 20.10 16.70 16.20 21.20 21.20 19.60 14.80

Chapter 7 Nonparametric Test Based on Ranks

Nonparametric Test Based on Ranks

1、Which of the following tests is NOT a non-parametric test?
A、Wilcoxon signed rank sum test
B、Friedman test
C、LSD test
D、test
E、Kruskal-Wallis test

2、We did a Wilcoxon rank sum test for the comparison of two groups. The observed values of group 1 were 0, 3, 7, 14; the observed values of group 2 were 0, 0, 2, 4, 4. What are the ranks of 0s in group 1 and group 2?
A、2, 2, 2
B、1.5, 1.5, 1.5
C、1, 1, 1
D、1, 2, 3
E、0s should be ignored.

3、The riboflavin was tested for 10 samples of cabbage under three test conditions (A, B, and C). The Friedman test showed that results under different test conditions are not all equal, at significance level 0.05. We want to know which pairs of test conditions are different. If Bonferroni method is used for multiple comparisons of mean ranks, the adjusted significance level should be:______
A、0.05/3
B、0.05
C、0.05/2
D、0.05×2
E、0.05/6

4、In the rank sum test, when the value of statistic T* falls within the range of critical values, then P is less than the corresponding probability.

5、Someone uses a nonparametric test to analyze the data which satisfied the t test condition. In general, it would increase the chance of making type II error.

Nonparametric Test Based on Ranks

1、In order to compare the differences in transverse diameter of porta pulmonis in different groups, 13 cancer patients and 15 healthy adults were randomly selected. Their transverse diameters of porta pulmonis were measured and data were listed in Table 1. Table 1. Transverse diameters (mm) of porta pulmonis Cancer patients (n=13) Health adults (n=15) 2.70 1.96 7.77 5.62 3.57 3.79 10.72 8.77 3.85 6.14 8.54 9.86 1.55 8.82 6.87 9.70 1.87 3.45 7.85 8.07 6.84 2.57 10.02 9.37 4.56 6.71 5.88 9.20 Questions: 1. If the data do not meet the requirements of parametric tests, what kind of method will you use? 2. What are the hypotheses of the statistical method you selected? 3. Please describe the steps of statistic calculation.

Chapter 8 Chi-square Test for Categorical Variable

Chi-square Test

1、In comparing effective rates between two groups, what are the possible factors that may influence the power for hypothesis testing?
A、Statistical significance level and difference in sample rates.
B、Difference in population rates and sample size.
C、Sample size and difference in sample rates.
D、Difference in population rates and expected frequencies.
E、Sampling error and statistical significance level

2、When row and column margins of a four-fold (2 × 2) table are fixed, if the actual frequency of one cell changes, the expected frequency of the corresponding cell will:______.
A、increase
B、decrease
C、not change
D、be uncertain
E、increase or decrease depending on the actual frequency of the cell

3、Each of the 97 blood samples were tested by coagulation test and ELISA respectively. Results are listed as below. To compare the positive rates of the two tests, which of the following tests is appropriate? Coagulation test ELISA Total 74 8 82 14 1 15 Total 88 9 97
A、Chi-square test
B、Chi-square test (with correction for continuity)
C、McNemar test
D、McNemar test (with correction for continuity)
E、Fisher’s exact test

4、Both articlesⅠandⅡcompared the effective rates of the two lipid-lowering drugs A and B. In articleⅠ, ,while in articleⅡ, it reported that . It can be concluded that articleⅠshowed that there was a larger difference in the effective rates of the two drugs.

5、For paired design of a 2×2 table, McNemar test can be used, the purpose of which is to test whether the positive rates of the two tests are the same or not.

Chi-square Test

1、Of the 121 patients with prostate cancer, 82 received electrosurgical therapy and 11 of them had postoperative complications; 39 received open surgery and 1 of them had postoperative complications. Is there any difference in the incidences of postoperative complications between the two treatments?

Chapter 9 Simple Linear Correlation

Simple Linear Correlation

1、X and Y follow a bi-variate normal distribution, their linear correlation coefficient r is quite near to 0. A hypothesis test for shows that P >0.90. What is the proper conclusion that we can draw?
A、There exists linear relationship between X and Y.
B、There exists strong relationship between X and Y.
C、There is no linear relationship between X and Y.
D、There is a curvilinear linear relationship between X and Y.
E、There isn’t any form of relationship between X and Y.

2、When we conduct an analysis of linear correlation, the variables X and Y should satisfy which of the following condition:
A、X and Y follow a bi-variable normal distribution.
B、Only X is required to follow a normal distribution.
C、Only Y is required to follow a normal distribution.
D、X and Y are quantitative variables without any pre-requisites to their distribution pattern.
E、X and Y are categorical variables.

3、In linear correlation analysis, a small P-value indicates that
A、There is a strong correlation between two variables.
B、There is a weak correlation between two variables.
C、The probability that we could reject H0 is high.
D、Sampling error is small.
E、Sampling error is big.

4、When , which one of the following statements is correct?
A、There is no association between two variables.
B、There is no linear association between two variables, but may exist a curvilinear association.
C、There is a linear association between two variables, and may exist a curvilinear association.
D、There is a curvilinear association between two variables.
E、It is uncertain of the association between two variables.

5、X and Y follow a bi-variable normal distribution, and the correlation coefficient r = 0.378 (P<0.05). What is the proper conclusion that we can draw?
A、There is not enough information for us to make a conclusion on the hypothesis test for
B、We cannot say there exists linear relationship between X and Y yet.
C、There exists curvilinear relationship between X and Y.
D、There exists positive correlation between X and Y.
E、There exists strong correlation between X and Y.

Simple Linear Correlation

1、Plasma albumin content (g/L) and hemoglobin content (g/L) of 15 normal adult males were measured by a physician, and the measurement results are shown in Table 1. Is there a correlation between the two variables? If so, what is the direction and strength of correlation? Table 1 Data on normal adult males’ plasma albumin content (g/L) and hemoglobin content (g/L) ID. albumin content hemoglobin content ID. albumin content hemoglobin content 1 35.40 120.1 9 35.6 108.2 2 36.30 121.2 10 34.5 105.3 3 38.60 127.8 11 35.5 108.7 4 37.40 126.7 12 36.5 112.6 5 36.60 120.9 13 34.8 109.4 6 34.40 117.8 14 35.7 108.6 7 34.50 110.6 15 34.8 105.4 8 34.20 109.3

Chapter 10 Simple Linear Regression

Simple Linear Regression

1、In simple linear regression analysis, if determination coefficient =1, then must hold_________.
A、r=0
B、r>0
C、r<0
D、r =1 or r =-1
E、b =1 or b =-1

2、We get Pearson’s correlation coefficient r >0. For the same set of data, regression equation is . Which of the following is true?
A、a>0
B、a<0
C、b=0
D、b<0
E、b>0

3、In linear regression analysis, the larger the is, the better the regression model will fit.
A、intercept
B、slope
C、regression coefficient
D、determination coefficient
E、t value when testing the significance of slope

4、The linear correlation and linear regression analyses were conducted based on the same sample, and correlation coefficient r is of statistical significance (P<0.001). Then, which of the following statement is correct
A、the slope b in regression analysis is of no statistical significance.
B、the slope b in regression analysis is of highly statistical significance.
C、the slope b in regression analysis is of statistical significance.
D、it is still uncertain whether the slope b in the regression analysis is of statistical significance.
E、the intercept a in regression analysis is of statistical significance.

5、Conducting both linear correlation and linear regression analysis for X and Y, which one of the following statements is correct?
A、rb≥0
B、rb≤0
C、r＞0，b＜0
D、r＜0，b＞0
E、r＝b

Simple Linear Regression

1、A doctor wanted to study the relationship between height (cm) and lung volume (ml) of children. He measured the height and lung volume of 10 children respectively. Please carry out regression analysis of lung volume on height. Table 1. Data on 10 children’s height (cm) and lung volume (ml) ID. height lung volume ID. height lung volume 1 110 34 6 137 51 2 112 46 7 147 65 3 122 62 8 150 56 4 123 56 9 154 70 5 130 60 10 155 62

Chapter 11 Statistical Principles of Experimental Design

Statistical Principles of Experimental Design

1、What is the difference between experimental group and control group?
A、Treatment
B、Effect
C、Sampling error
D、Observation time
E、Location

2、The best control method for confounding bias is _________.
A、Restriction
B、Matching
C、Random grouping
D、Balanced processing
E、Statistical processing

3、In the case-control study of obesity and hypertension, the cases were from patients found by medical examination in a hospital, and the control was an employee of an enterprise located in the hospital. The design may exist .
A、Sampling error
B、Gross error
C、System error
D、Selection bias
E、Confounding bias

4、A doctor used a triple therapy to treat 120 cases of peptic ulcers, a total of 105 cases were observed to be effective, with an efficiency of 87.5%, so it is considered that this therapy has a better effect. The analysis .
A、failure to implement the principle of randomization
B、insufficient sample size
C、no control group
D、failure to implement the principle of duplication
E、right

5、Inappropriate sampling methods may result in samples that do not represent the population well.

Chapter 12 Statistical Tables and Charts

Statistical Tables and Charts

1、Using statistical tables and charts must be more clearly than text.

2、Make sure the statistical tables and charts can stand alone from the text.

3、Values to be compared should be placed side-by-side.

4、Using charts is that a minimum of information can be conveyed in a maximum of space.

5、Different academic journals sometimes give their own special regulations.

Final Test

Final Test

1、To know the average level of lung capacity of students at a university, an investigator measured lung capacity of 500 students randomly sampled from the university. The whole collection of measured lung capacity is a .
A、sample
B、population
C、variable
D、statistic
E、parameter

2、The term “population” in statistics is defined as _________.
A、the whole collection of research objects who are imagined arbitrarily
B、the whole collection of research objects who are determined by research objective
C、the whole collection of research objects who are determined by period of time
D、the whole collection of research objects who are determined by race
E、the whole collection of research objects who are determined by region

3、Which of the following statistics is appropriate to compare the variation of height and weight of students in a university?
A、Variance
B、CV
C、Range
D、S
E、Q3-Q1

4、Which of the following is not a qualitative variable: ______.
A、The therapeutic effect of a drug (effective, ineffective)
B、Antibody titer levels after immunization (-, -/+, +, ++, +++)
C、Education level (primary, junior high, high school, university, university or above)
D、The weight of 120 participants of a survey in a certain area
E、Patients’ grading of disease (mild, moderate and severe)

5、μ and are the two parameters for a normal distribution. In which situation the curve of probability density function of a normal distribution will become narrow?
A、When μ becomes larger.
B、When μ becomes smaller.
C、When σ becomes larger.
D、When σ becomes smaller.
E、When μ and σ both become larger.

6、If variable X follows a Binomial distribution which of the follow is NOT true?
A、 is a discrete distribution
B、If π>0.5, is positively skewed.
C、The population mean of P is π
D、The population mean of X is nπ
E、If n is large enough, approximates to a normal distribution

7、In the research based on sampling, when sample size is larger, _________.
A、standard error increases
B、standard deviation increases
C、standard deviation decreases
D、standard error decreases
E、standard deviation tends to be zero

8、Assume the overall serum cholesterol follows a normal distribution among healthy people. 95% confidence interval for overall serum cholesterol based on a sample of 100 healthy individuals is 4.804 ~ 5.196 mmol/L，then 95% two side reference range is .
A、5.00±1.960×10
B、5.00±1.645×
C、5.00±1.96×
D、5.00±1.960×1
E、5.00±1.645×1

9、If statistical inference is to be made through the sample, the sample should be_____
A、the most typical part of the population.
B、any part of the population.
C、the part randomly selected from the population.
D、the most meaningful part of the population.
E、the most explicit part of the population.

10、If a t-test shows the difference between two sample means is statistically significant, then the smaller the P value is
A、the greater the difference between the two sample means.
B、the greater the difference between the two population means.
C、the more reasonable to conclude that the two samples are different.
D、the more reasonable to conclude that the two populations are different.
E、the smaller the probability of making a mistake when rejecting the null hypothesis.

11、Standard error is used to reflect the variation of: .
A、Sample mean
B、Individual value
C、Sample median
D、Inter-quartile range
E、Frequency

12、Analysis of Variance (ANOVA) is a test for the difference in .
A、means of two or more samples
B、means of three or more samples
C、vairance of three or more smaples
D、means of two or more populations
E、variance of two or more populations

13、Which of the following is not a precondition for Analysis of Variance: .
A、Normality
B、The homogeneity of three variances
C、Independence of the data
D、Numerical variables
E、Equal group means

14、In ANOVA for the completely randomized design, there must be:
A、
B、
C、
D、
E、

15、270 people with diabetes are randomly divided into three groups and treated with A, B and C methods, respectively. The difference of blood glucose before and after taking the medicine is taken as the effect. To compare the effects of the three methods, which one the following statements is correct:
A、t-test for comparison of the differences among the three samples should be used.
B、t-test for pairwise comparison should be used.
C、ANOVA for comparison of the differences among the three samples should be used.
D、ANOVA for randomized block design should be used.
E、None of the above is correct.

16、Which of the following statement about test of contingency table is correct?
A、Can’t be used for the fourfold table.
B、Can only be used to compare several sample rates.
C、Can be used for the comparison of two proportions.
D、It suggests any two population rates/ proportions are different if H0 is rejected.
E、Can be used for the paired table.

17、Which of the following statements about the probability is WRONG?
A、Probability is the measure of the likelihood that an event will occur.
B、Any probability takes value from the interval [0,1].
C、The event with probability of 0 is called an impossible event.
D、The frequency of an event E is exactly the probability of the event E.
E、In practice, the probability is difficult to be obtained.

18、To test whether urine sugar levels are associated with aspirin intake, a researcher tested the urine sugar levels (positive or negative) of 300 randomly-selected outpatients from a hospital, of whom 150 had taken aspirin on a long-term basis and the rest did not use the medicine before. Which test should be used for the statistical analysis?
A、Simple linear correlation analysis
B、t test for two independent groups
C、t test for two paired groups
D、Chi-square test for two independent groups
E、Chi-square test for two paired groups

19、A physician wants to compare the effects of three therapies for a certain disease. Under group A there were 21 cases, of which 12 got better and 9 showed no progress, the group B treated 23 cases, of which 18 got better, and the group C treated 22 cases, of which 19 got better. If the test is performed on this data, the degree of freedom should be .
A、65
B、64
C、63
D、3
E、2

20、If the preconditions for parametric methods are satisfied, compared with parametric methods, using non-parametric methods will
A、takes more chance to make Type I error.
B、takes more chance to make Type II error.
C、takes less chance to make Type I error.
D、takes less chance to make Type II error.
E、takes more chance to make both types of error.

21、When Wilcoxon's rank sum test is applied for comparing the locations of two distributions, if the number of identical ranks is too large, the ties should be adjusted. After adjustment, what is the proper result that we can get?
A、The value of Z decreases, P value increases.
B、The value of Z decreases, P value decreases.
C、The value of Z decreases, P value decreases.
D、The value of Z increases, P value increases.
E、The value of both Z and P are not changed.

22、When we use rank sum test to compare two samples:______.
A、The same sample sizes are required
B、Rank all the observations one by one orderly and omit zero
C、Rank all the observations one by one orderly and give a mean rank to the same value
D、It’s a parametric test if the statistic Z is calculated when the sample sizes are large enough
E、None of the above

23、Which one of the following is NOT appropriate for describing the linear correlation coefficient?
A、The value of linear correlation coefficient is between -1 and 1
B、The linear correlation coefficient does not have a unit.
C、For a ρ=0，there must be curvilinear association.
D、For a ρ≠0，r>0 indicates positive association.
E、It can be used to describe the strength of association.

24、To explore the dose-response relationship of a new medicine, k dosages of the medicine (variable X) are fixed by the researcher in advance. The response (variable Y) is a continuous variable. The researcher got 0.86 by the formula of linear correlation coefficient between X and Y. Which of the following statements is correct?
A、We cannot say there is a positively linear correlation between X and Y unless the hypothesis testing is conducted.
B、We can conclude that there is a positively linear correlation between X and Y based on the sign of the correlation coefficient.
C、The choice of linear correlation analysis is unreasonable as X is not a random variable.
D、We can conclude that there is a strong linear correlation between X and Y based on the absolute value of the correlation coefficient.
E、We can say there is a positively strong linear correlation between X and Y.

25、There are two pairs of random variables (X1 and Y1, and X1 and Y2) which following a bi-variable normal distribution respectively. Linear regression analyses are conducted based the two pairs of variables. The results show that b1=0.83 (P=0.015) and b2=0.65 (P=0.005). Which of the following statement is correct?
A、r1> r2
B、r1< r2
C、ρ1>ρ2
D、ρ1<ρ2
E、There is no fixed relationship between r1 and r2.

26、In simple linear regression analysis, SSresidual indicates _________.
A、the variation in Y
B、the variation in Y has not be explained by X
C、the variation in
D、the variation in has not be explained by X
E、the variation in regression coefficient (b)

27、X and Y follow a bivariate normal distribution. After a regression of Y on X, the regression coefficient b = 0.416 (P<0.05), and the correlation coefficient r = 0.378. What is the proper conclusion that we can draw?
A、There is not enough information for us to make a conclusion on the hypothesis test for H0: ρ=0.
B、We cannot say there exists linear relationship between X and Y yet.
C、There exists curvilinear relationship between X and Y.
D、The determination coefficient equals
E、The determination coefficient equals

28、In a study on evoked potentials, participants in group A were asked to use the calculator to complete the multiplication of numbers under 100. Participants in group B were asked to complete the same question using mental arithmetic. To compare the proportion of fast waves (β waves) between the two groups, identical twin sisters were randomly assigned to groups A and B. What is the corresponding research design?
A、Completely random design
B、Paired design
C、Blind design
D、Repeated measurement design
E、Completely randomized block design

29、In the research mentioned in the above question, one of the interventions is considered as the standard occupational intervention at present. What is the type of control used in this research?
A、Active control
B、Placebo control
C、Dose-response control
D、Experimental control
E、null control

30、To estimate the prevalence of breast cancer among adult women in Guangzhou city, a research institute randomly selected 50 communities out of all communities in Guangzhou, and then investigated all adult women in each selected community. What sampling method was used in this survey?
A、Cluster sampling
B、Systematic sampling
C、Stratified sampling
D、Simple random sampling
E、Non-random sampling

31、To describe the relationship between age (divided into eight groups) and blood pressures, which of the following statistical graphs should be plotted.
A、Line chart
B、Pie chart
C、Histogram
D、Percentile bar chart
E、Box chart

32、Comparing the prevalence rate of several diseases in a certain place over two years, the most suitable statistical graph is_________.
A、histogram
B、simple bar chart
C、clustered bar chart
D、line chart
E、pie chart

33、Which of the following does not belong to the purpose of the histogram or frequency distribution table?
A、Visually indicate the distribution type of data.
B、Describe the central trend and dispersion trend of data.
C、Perform statistical inference on the type of data distribution.
D、Verify the data quality.
E、Frequency distribution tables can be used to calculate the statistic of central trend and dispersion trend.

34、Which method should be used to compare the positive rates of serological tests after hepatitis C vaccination in three cities?
A、ANOVA
B、Rank sum test
C、Depends on if data meet the conditions of ANOVA or rank sum test
D、Linear correlation analysis
E、Chi-square test

35、A radiologist collected 60 patients with brain trauma and measured the area of cerebral hemorrhage and the degree of coma (mild, moderate, and severe) of each patient. To assess the relationship between these two variables, the radiologist could perform _________.
A、Pearson’s linear correlation analysis
B、Spearman's rank correlation analysis
C、t test for two independent samples
D、ANOVA
E、Chi-square test

36、In Statistics, “parameter” is a measurement to describe the sample.

37、Two main statistical methods are used in data analysis: descriptive statistics, which summarize data from a sample, and inferential statistics, which draw conclusions from data that are subject to random variation.

38、The mean and the standard deviation will change if each observation in the sample is added (or subtracted) by the same number.

39、Interquartile range is mainly used to describe the variation of normally distributed data.

40、Probability is the measure of the likelihood that an event will occur.

41、For a Poisson distribution, the mean is equal to the variance.

42、A proper sampling method can avoid the occurrence of sampling error.

43、So-called “95% confidence interval for population mean” is applied to estimate the location of population mean, with a confidence level 95%.

44、P value is the probability of the event that the current situation and even more extreme situation based on the assumption that alternative hypothesis is satisfied.

45、In the rank sum test of ordinal variables, the average rank of each category is the lower bound of the corresponding range of rank.

46、For the hypothesis test whether the population correlation coefficient is 0, the smaller the P value, the closer the relationship between the two variables.

47、Known that a correlation coefficient r comes from the population with ρ≠0, then r>0 indicates a positive correlation, and r<0 indicates a negative correlation.

48、In two sets of data, two variables with a larger regression coefficient b are more closely related than variables in the other dataset.

49、The principle "randomization" to be followed in interventional design means that the sample size of each interventional group is equal.

50、A scatter plot can be drawn to describe the relationship between lung capacity and height in 300 people.

学习通Medical Statistics

学习通是一款面向全球用户的在线学习平台，提供了丰富的课程资源，其中包括医学统计学。作为医学科研领域的重要组成部分，医学统计学的学习对于医学研究和临床实践具有重要意义。

医学统计学介绍

医学统计学是一门研究医学数据的统计学科，常见的应用包括医学研究设计、数据采集、数据分析和研究结果的解释等方面。医学统计学所涵盖的内容非常广泛，包括描述性统计、概率论、假设检验、方差分析、回归分析等等。

医学统计学的主要目的是为了从大量数据中发现变量之间的相互关系和规律，以便更好地理解和应用这些数据。通过医学统计学的学习，可以帮助医学研究人员和临床医生更好地利用和解释研究结果，提高研究效率和临床治疗质量。