24. Rosalie Friend (2001), and educational psychologist, compared three methods of teaching writing. Students were randomly assigned to three different experimental conditions involving different methods of writing a summary. At the end of the two days of instructions, participants wrote a summary. One of the ways it was scored was the percentage of specific details of information it included from the original material. Here is a selection from her article describing one of the findings:

Question

24. Rosalie Friend (2001), and educational psychologist, compared three methods of teaching writing. Students were randomly assigned to three different experimental conditions involving different methods of writing a summary. At the end of the two days of instructions, participants wrote a summary. One of the ways it was scored was the percentage of specific details of information it included from the original material. Here is a selection from her article describing one of the findings:

The effect of summarization method on inclusion of important information was significant F(2, 144) = 4.1032, p < .019. The mean scores (with standard deviations in parantheses) were as follows: Argument Repetition, 59.6% (17.9); Generalization, 59.8% (15.2); and Self-Reflection, 50.2% (18.0). (p.14)

a. Explain these results to a person who has never had a course in statistics.
b. Using the information in the preceding description, figure the effect size for the study.

Answer 1

Is there an answer to this

Answer 2

a. In this study, Rosalie Friend compared three different methods of teaching writing. The goal was to see how these different methods influenced the inclusion of important information in the summaries written by the students. To understand the results, we need to look at the statistical information provided.

The result is described in terms of a statistical test called "F-test" or "ANOVA". The F(2, 144) value of 4.1032 represents the result of this test. The numbers in parentheses after the mean scores represent the standard deviations, which provide an indication of the variability of the scores.

The p-value is also mentioned as being less than .019. This p-value is used to determine the statistical significance of the findings. In this case, a p-value less than .019 indicates that the difference in the mean scores among the three methods is statistically significant.

To summarize, the statistical analysis shows that the method used to teach writing significantly influenced the inclusion of important information in the summaries written by the students. The mean scores suggest that the Argument Repetition and Generalization methods resulted in higher percentages of important information compared to the Self-Reflection method.

b. To calculate the effect size, we need to use the information provided in the description. The mean scores for each method are given as follows:
- Argument Repetition: 59.6%
- Generalization: 59.8%
- Self-Reflection: 50.2%

To calculate the effect size, we can use Cohen's d, which is a measure of the difference between the means divided by the standard deviation. In this case, since we have three means, we can calculate the effect size for each pair of means and then take the average.

For the Argument Repetition method and Generalization method:
Effect size = (Mean1 - Mean2) / (Average standard deviation)
= (59.6 - 59.8) / ((17.9 + 15.2) / 2)

For the Argument Repetition method and Self-Reflection method:
Effect size = (Mean1 - Mean3) / (Average standard deviation)
= (59.6 - 50.2) / ((17.9 + 18.0) / 2)

For the Generalization method and Self-Reflection method:
Effect size = (Mean2 - Mean3) / (Average standard deviation)
= (59.8 - 50.2) / ((15.2 + 18.0) / 2)

Once the effect sizes for each pair of means are calculated, we can take the average of these effect sizes to get the overall effect size for the study.