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Stat 301 Lab 2 Due September 15, 2014 Last week's lab looked at data on the heights of children ages 3 to 19. The data are available on the course Web site: http://www.public.iastate.edu/~wrstephe/stat301.html In this week’s lab assignment we will look at whether gender of the child can explain some of the variability in children’s heights. You should use JMP to perform an analysis to compare the heights of Males to those of Females. It is not sufficient to simply hand in JMP output. You must answer the questions completely. Turn in the JMP output attached at the end of your written answers. 1. Two-sample problem. a) Summarize the heights graphically and numerically for each gender. How do male heights compare to female heights? b) Are males significantly taller than females in terms of population mean heights? Perform the appropriate test of hypothesis. Use α=0.05. c) Report the value of a 98% confidence interval for the difference between the population mean height for males and the population mean height of females. Give an interpretation of this interval. d) Is the confidence interval in c) consistent with your test of hypothesis in b)? Explain briefly. e) Use JMP to create the residuals for the two genders, male and female. Use Analyze + Distribution to create JMP output that looks at the distribution (histogram, box plot and Normal Quantile Plot) of the resulting 100 residuals. f) Refer to the histogram of residuals and indicate what you see and what this tells you about the condition that the random errors are normally distributed. g) Refer to the box plot of residuals. Are there any possible outliers? If so, what are the corresponding heights and genders? What does the box plot tell you about the random errors being identically distributed? h) Refer to the Normal Quantile Plot of residuals and indicate what you see and what this tells you about the condition that the random errors are normally distributed? i) Comment on whether or not the data are consistent with the condition that both populations (male and female) have the same standard deviation. This will require further analysis with JMP. j) Summarize what you have learned about the conditions necessary for statistical analysis of the data on heights from your analysis of residuals. 2. On a separate piece of paper (this sheet will be graded separately from your answers to part 1) write a brief summary of what you have learned about heights of male and female children between the ages of 3 and 19.