Week 13 - Assignments

Statistics

Question 15

What is the major distinction between the Pearson and Spearman correlations?

Question 17

A common concern for students (and teachers) is the assignment of grades for essays or term papers. Because there are no absolute right or wrong answers, these grades must be based on a judgment of quality. To demonstrate that these judgments actually are valid, an English instructor asked a colleague to rank-order a set of term papers. The ranks and the instructor’s grades for these papers are as follows:

Rank Grade

1. A
2. B
3. A
4. B
5. B
6. C
7. D
8. C
9. C
10. D
11. E
    1. Calculate the Spearman correlation for these data. (Note: You must convert the letter grades to ranks.)
    2. Based on this correlation, does it appear that there is reasonable agreement between the two instructors in their judgment of the papers?

Question 21

To test the effectiveness of a new studying strategy, a psychologist randomly divides a sample of 8 students into two groups, with n = 4 in each group. The students in one group receive training in the new studying strategy. Then all students are given 30 minutes to study a chapter from a history textbook before they take a quiz on the chapter. The quiz scores for the two groups are as follows:

Training No Training

9 4

7 7

6 3

10 6

1. Convert these data into a form suitable for the point-biserial correlation. (Use X = 1 for training, X = 0 for no training, and the quiz score for Y.)
2. Calculate the point-biserial correlation for these data.

SPSS Assignment

Review pp. 25–30 in SPSS Assignments.doc (provided under Doc Sharing ). This section discusses the steps and features of the Crosstabs command.

There has been much debate in the United States over the "digital divide": the gap (some would say growing gap) between "technology haves" and "technology have-nots" and the impact this has on learning. For this assignment, we want to see, using the frss79spec.sav data, whether or not there is indeed a gap for schools, based upon characteristics of the student population or the location of the school. To do this, we will use the following variables from frss79spec.sav:

• nminstat : percentage of the student population which is minority
• freelnch : classified grouping of percentage of student population eligible for free lunch program

And

• Q7cb: To what extent do students use the Internet?

(1) In the variable view of SPSS, make sure that the Value Labels for each of the four variables are entered, using the codebook (layoutreadme.rtf, provided under Doc Sharing ) as the source for the Value Labels. (For a refresher on creating Value Labels, refer to pp. 15–16 in SPSS Assignments.doc.)

(2) Use Analyze>Descriptive Statistics> Crosstabs to crosstabulate the following pairs:

When specifying the crosstabulation, be sure, under "Statistics" to check that you want the Ordinal statistics tau-b and gamma. You use the Ordinal correlations since these are ordinal-level variables.

(3) Copy or copy object and paste relevant output from the statistical tests.

(4) Write a one-paragraph analysis of the output which assesses whether or not there is a relationship between student computer use and the percent minority students and/or the percent eligible for free lunch.

Price: $14.68

Solution: The downloadable solution consists of 7 pages, 768 words and 4 charts.
Deliverable: Word Document