Clinical observations suggest that specifically language-impaired (SLI) children have great difficulty with the proper use of pronouns. This phenomenon was investigated and reported in the Journal of Communication Disorders (Mar. 1995). Thirty children, all from low-income families, participated in the study. Ten were five-year-old SLI children, 10 were younger (three-year-old) normally developing (YND) children, and 10 were older (five-year-old) normally developing (OND) children. The table contains the group, deviation intelligence quotient (DIQ), and percentage of pronoun errors observed for each of the 30 subjects. (The data for these variables, as well as gender, are saved in the SLI file.)

a. Identify the variables in the data set as quantitative or qualitative.
b. Why is it nonsensical to compute numerical descriptive measures for qualitative variables?
c. Compute measures of central tendency for DIQ for the 10 SLI children.
d. Compute measures of central tendency for DIQ for the 10 YND children.
e. Compute measures of central tendency for DIQ for the 10 OND children.
f. Use the results from parts c€“e to compare the DIQ central tendencies of the three groups of children. Is it reasonable to use a single number (e.g., mean or median) to describe the center of the DIQ distribution? Or should three €œcenters€ be calculated, one for each of the three groups of children? Explain.
g. Repeat parts c €“ f for the percentage of pronoun errors.
*h. Plot all the data to investigate a possible trend between DIQ and proper use of pronouns. What do you observe?
*i. Plot the data for the 10 SLI children only. Is there a trend between DIQ and proper use of pronouns?

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YND SLI OND DIQ Pronoun Errors (%) DIQ Pronoun Errors (%) DIQ Pronoun Errors (%) 110 92 92 100 86 105 90 96 90 92 94.40 19.05 62.50 18.75 0.00 55.00 100.00 86.67 32.43 0.00 86 86 94 98 89 84 110 107 87 95 60.00 40.00 31.58 66.67 42.86 27.27 33.33 0.00 0.00 0.00 110 113 113 109 92 108 95 87 94 98