Lecture11 review for final examination Xiaojinyu@seu.edu.cn Department of Epidemiology and Biostatistics

Final assessment 60% big class quizzes(3) and final writing examination 40% from computer lab

Examination 1. Single Choice 20’ 2. terms 3.simple question 4.Complicated question

Simple choice (A) The range is a measure of central tendency. 1. Which of the following statements is correct? (A) The range is a measure of central tendency. (B) The median is a measure of dispersion. (C) For a symmetric distribution, the mean is equal to the median. (D) For a skewed distribution, the variance is a negative number. 2. There are 100 men., with mean 171.06cm and standard deviation 4.95cm.in heights ,with mean 61.54kg and standard deviation 4.72kg in weights. Which of the following statements is true? (A) The variation of the weight is higher than that of the height. (B) The variation of the height is higher than that of the weight. (C) The variation of the height is same as the weight. (D) The variation of the height and that of the weight are not comparable because of different units. 3. A study is conducted among the students in a statistics class, and several variables are recorded, please judges which of following variables are categorical or quantitative. (A) The blood types of the students are quantitative. (B) The credit hours available during that semester are quantitative. (C) The time that students spend waiting in line at the bookstore to pay for his/her textbooks is categorical. (D) The hometown of the student is quantitative.

Summary of Terms Population sample Sample size Parameter Probability Statistic CI RI Sampling error Median CV SD SE Significance level Ratio Proportion Randomization Rank sum Correlation coefficient Regression coefficient

Simple question Question1 What are the sample mean (to 2 decimal places) and median of the following data? 15, 21, 24,16,13,18 Question2 What is difference between SD and SE?

Simple question Question 3 What is difference between CI and RI?

Simple question Question 5 Please give 2 examples of qualitative binary categorical data, and ordinal data variables respectively. Quantitative: binary data: Ordinal data:

Simple question The means and SDs of height and weight are followed. How to compare the variation of height and weight of a group of boys of age 12. weight: mean=40Kg  variance=16kg  height: mean=140cm  variance=28cm  Solution: CV1=16/40=0.4 CV2=28/140=0.2 So weight has more dispersion than height

Simple questions Quiz1 Quiz2

More simple question How to control the sampling error? Solution: 1.to increase sample size 2.to decrease variation, What are the differences among cardinal data, ordinal data? (explain with examples) What is the difference between a parametric test and a nonparametric test?

Complicated question Quiz3-4 Quiz5 t-test for 2 independent groups. A study was carried out to investigate the effectiveness of a treatment.50 subjects participated in the study, with 25 being randomly assigned to the “treatment group” and the other 25 to the “control (or placebo) group”. Some results are listed as follows. Please answer these questions

Complicated question a. what are the hypotheses for this question? b. If the t value of significance test is 7.139, how much df and p value? (the critical value is t0.05/2,40=2.021 or t0.05/2,50=2.009) c. What is statistical conclusion? d. what is medical conclusion?

Complicated question Chi-square test Rank sum test

Thank you for your attention!