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LSP 121 -- Homework 1

Descriptive Statistics with SPSS

1. In class, each group of two or three will use this online stopwatch to time how long it takes each person in the group to count off thirty seconds. Keep your eyes closed while counting and no cheating.

2. The professor will collect these numbers and post these times in the Excel file human-clocks.xls.

3. Use SPSS to do the following using times from the human-clock dataset. Keep relevant output, not SPSS source code and reporting. Export the relevent output in an MS Word file and type comments for the starred items at the top of the document to show that you found the information:
   1. *Find Q0, Q1, Q2, Q3, and Q4.

   2. Draw the boxplot. *Are there any outliers? Explain your answer.

   3. *Find the sample mean and SD+.

   4. Draw a histogram.

   5. Add a column of z-scores to the dataset. Print the resulting dataset.

   6. You already know how to use the boxplot to detect outliers (Method 1). Using the z-scores is another method to detect outliers (Method 2). An extreme outlier is an observation with z-score greater than 3 or less than -3. A mild outlier is an observation with z-score greater than 2 or less than -2, but which is not an extreme outlier.

      *Are there any outliers according to Method 2. Print your z-scores with Analyze >> Reports >> Case Summaries. Also, explain your answer.