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Lecture11 review for final examination

This review will cover topics such as central tendency, dispersion, categorical and quantitative variables, variation comparison, sampling error, and parametric vs nonparametric tests.

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Lecture11 review for final examination

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

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

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

  4. Simple choice • 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.

  5. 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 Summary of Terms

  6. 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?

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

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

  9. 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

  10. Simple questions • Quiz1 • Quiz2

  11. 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?

  12. 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

  13. 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?

  14. Complicated question • Chi-square test • Rank sum test

  15. Thank you for your attention!

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