Programming Assignment 1

CSC 323 - Data Analysis and Statistical Software

Due: Section 602: 5/1/2002 & Section 603: 5/2/2002

You have been assigned to a software development team that is conducting a series of usability tests on a new version of a browser based user interface. The interface has been designed with expert users in mind and so has features to accommodate such users (see the Novice vs. Expert Users essay from Jakob Nielsens useit.com site).

Your team observed twenty nine randomly selected expert users as they worked on a suite of tasks. You have been presented with the data collected and have been asked to do a basic analysis.

Each observation in your file consists of the following values:

Notice that the times provided are for the individual tasks in the suite. You are interested in the time to complete the suite of tasks.

The requirements for your analysis are detailed below:

  1. Write a SAS program to analyze these data. Remember, your program should analyze suite completion time not individual task times. (50%)
    Your program should accomplish the following:

    1. Access your data from an external file.
    2. Compute suite completion time. That is, the total time to complete the suite of four tasks. If necessary, see "DATA step statements", point 6, SAS Review.
    3. Execute the PRINT and MEANS procedures with appropriate options.
    4. For PROC PRINT, be sure to use labels for column headings (e.g. Suite Completion Time, Number of Errors, User ID, Observer ID, Satisfaction Score). Use names that are meaningful. You should generate an appropriate title for your output.
    Note: If necessary, see the SAS program used for the in-class SAS demonstration.

  2. Write a short report (no more than a couple of paragraphs) discussing your findings. (50%)
    Your report should address the following:

    1. Provide an estimate of the population mean (3 places of decimal). That is, the mean suite completion time for all expert users.
    2. Provide an estimate of the population standard deviation (3 places of decimal). That is the standard deviation of suite completion time for all expert users.
    3. Your boss has asked you to address the following in your report (include all computations and diagrams to support your answer):
      • If some expert user required 350 seconds to complete the suite, what would be his percentile rank.
      • Determine the suite completion time that distinguishes fast expert users from others. Fast expert users are the quickest 25% of expert users.
      Note: To address these questions, assume that suite completion time is normally distributed. Also, use your estimates of the relevant population parameters.