Programming Assignment 2

CSC 323 - Data Analysis and Statistical Software

Due: 3/1/2001

A large internet retailer has hired you as a software engineer. The team that you have been assigned to is conducting a series of usability tests on a new user interface intended for expert users (see the Novice vs. Expert Users essay from Jakob Nielsens useit.com site).

Your team must demonstrate that the proposed interface will allow expert users to complete tasks more efficiently than the existing interface. You have been asked to assist with a controlled experiment involving twenty six expert users selected from a database of repeat customers. The purpose of this experiment is to determine if the proposed interface allows expert users to complete a standard task suite more quickly than the existing interface. Studies indicate that the mean time required to complete the task suite with the existing interface is 380 seconds.
Note: See the Usability Metrics essay for additional details on usability as well as details of a similar experiment conducted by Macromedia.

You have been presented with the data collected for this experiment. Each observation in the file consists of the following values:

• Observer ID; 1-5
• User ID; 6-10
• Task Time (seconds); 11-13
• Error Count; 14-15
• Satisfaction Score; 16-17

Conduct a thorough analysis of these data. You will need to conduct a test of hypotheses and submit a report summarizing your findings. See additional details below.

1. Write a SAS program to analyze this dataset. Your program should do the following:
1. Read your data from an external file.
2. Execute the PRINT procedure.
3. Use the appropriate SAS procedures to produce the statistics and p-values to test your hypotheses.

Note: For PROC PRINT, be sure to use labels for column headings rather than variable names. Use names for data sets and variables that are meaningful. You should generate an appropriate title for the output of these procedures.

2. Write a short analysis (no more than two pages) of the output of your SAS program. Your analysis should at least address the following:
1. State the primary hypotheses. That is, the NULL and ALTERNATIVE hypotheses for the experiment described above.
2. State and address any other hypotheses needed for your analysis.
3. Discuss the significance of the p-value obtained for the primary hypotheses.
4. Given your findings, briefly explain why you should (or should not) provide a point estimate for the parameter in question. If you argue that a point estimate for the parameter is appropriate you must provide it as well as a 95% confidence interval for the parameter (with an interpretation).