A Visual Approach to SPSS for Windows 2nd Edition by Leonard Stern

تمرين 3

Note: Data files for these exercises are available at the publisher's website for this text, http://www.pearsonhighered.com/stern2e.
As previously described in Exercise 1 , the file FalseRecognitionExp.sav contains the proportion of words recognized in an experiment by participants who were tested on three categories of words: words that were not presented in lists of strong associates of the missing word (variable preccnp , referred to here as condition 1); words that were presented in lists of strong associates of the presented word ( preccpp , referred to here as condition 2); or words that both were neither presented nor had any lists of strong associates presented ( preccnn , referred to here as condition 3). Determine whether the mean of condition 1 differs significantly from the mean of condition 2, and whether the mean of condition 2 differs significantly from that of condition 3. Treat these analyses as planned comparisons.
Because the A values 56,.64, and.71 correspond to small, medium, and large effect sizes, respectively, the effect size obtained for our example can be described as large. Note that because A 12 =1 A 21 , , the value A classical, rock is.28.
The outcome of the Wilcoxon signed-ranks test illustrated above can be summarized as follows:
To determine whether math performance differs when students solve problems with classical vs. rock music in the background, the number of problems solved in 20 minutes was recorded for nine randomly selected students who were exposed to four alternating 5-minute periods in which classical or rock music was played. The median number of problems solved with the classical music background was 9.00 and that with the rock music background was 12.00. This difference, tested with a Wilcoxon signed ranks test was significant, z = 1.98, p.05. For this test, the smaller sum of ranks, based on two pairs of scores, had the value of 4.00. Of the nine paired scores one pair of ranks was tied. The A value for the effect was.72, which corresponds to a large effect (Vargha and Delaney, 2000).
Exercise 1
The file FalseRecognitionExp.sav contains the proportion of words recognized in an experiment by participants who were tested on three categories of words: words that were not presented in lists of strong associates of the missing word (variable preccnp ); words that were presented in lists of strong associates of the presented word ( preccpp ); or words that both were neither presented nor had any lists of strong associates presented ( preccnn ).
1. Prepare a table that shows the means of the three variables in descending order. Include in the table each variable's standard deviation, minimum, and maximum value.
2. Present a single boxplot of the three variables. Use the variable name to label cases. What does the plot reveal about the shape of the distribution of each variable and about the presence of unusual scores