Stat31-5

Class project: Part II. Exploratory Analysis of Variables, one at a time.

Instructions: Assigned on 09-17-03 and due on 09-24-03. Show your work for every question, and return it with your circled answers on a sheet of paper in class on 09-24-03. In addition, send an Excel file with your data along with any graphic or computation you made by email to rizem@email.unc.edu (with subject: Class project part2) by the day the assignment is due before 1pm.

Questions:

0. Give a title to your class project.

1. Make a graphic showing the distribution of each variable in your data set.

2. Describe the overall pattern of each distribution.

3. Writing formulas and Excel formulas:

a) Write the mathematical formula for the sample mean and the sample standard deviation.

b) Suppose your data for one variable is on rows 2 to 32 of column B in your Excel spreadsheet. Write the following two excel formulas: excel formula to find the sample mean of this variable, and excel formula to find the sample standard deviation of this variable. (There are several correct answers for this question, give only one answer).

4. For each one of the two continuous quantitative variables, answer the following questions:

c) Find the sample mean and the sample standard deviation.

d) Give the five number summary.

e) Which measure of center and spread would you use in this case and why?

f) Are there any outliers in this data? Why?

h) Make a modified boxplot.

5. Would the normal distribution be a reasonable approximation to the distribution of one of your quantitative variables? Why? Or Why not?

(Hint: compare shape and also median and quartiles of your variable with those of a normal distribution with mean m (respectively, standard deviation s) equal to the xbar of your variable (respectively, the s of your variable))