Problem Set 2: Minitab Basics
Consider the dataset 95WORLD.DAT from the class website, and solve the following problems. Details on the variables can be found in the workbook, pg 17.
Any output (session window, graphs) you produce to help you answer these problems should have a time stamp and your name on it.
Problem 1. We wish to explore life expectancy for women and men for all countries. a) Produce descriptive statistics of the two variables. Which gender seems to have higher life expectancy at first glance?
b) To obtain an idea about the distribution of the two variables, obtain histograms
(with normal curves). What can you say about the shape of the two distributions? c) Conduct a formal normality test for both variables and report the p-values for the
Anderson-Darling test. Are the two variables normally distributed? Justify based on the p-values. d) Suppose we wish to test the claim that women live more than 65 years, on the average, based on all countries. First formulate appropriate null and alternative hypothesis and report them below. e) Which test is appropriate and why? f) Conduct the test you chose in part e) to test the claim of part d) with a=.01. Report the value of the appropriate test statistic (Z or t) and its p-value. Do you reject the claim? Explain. g) Repeat parts d)-f), but now test for more than 70 years with a=.01. Report the pvalue and interpret. Is your conclusion different than in part f)? Explain why.

h) Suppose we wish to examine whether the mean life expectancy for women is longer in countries where daily the calorie intake is high (>2500). First create the two samples of countries based on calorie intake and then test the claim at a=.05.
Report below appropriate null and alternative hypotheses, the value of the test statistic and its p-value. Do you reject the claim?
Hint: Follow the steps in the workbook pg 23. i) Now examine whether the mean life expectancy for women is higher than that for men. First obtain a 95% CI for the difference between average life expectancies.
Test the claim at level a=.05, and discuss the results. Why is a paired t-test appropriate in this case? j) Finally, produce a scatter plot between the two life expectancies. Is there a linear trend? What does it mean in terms of the variables involved? Obtain the Pearson correlation coefficient to help you interpret these results.
Hints: Use the following menu items appropriately:
Stat>Basic Statistics>Display Descriptive Statistics
Stat>Basic Statistics>Normality Test
Stat>Basic Statistics>1-Sample Z or t
Stat>Basic Statistics>Paired t
Stat>Basic Statistics>2-Sample t
Calc>Calculator
Graph>Scatterplot
Stat>Basic Statistics>Correlation