Exam 11: The Hypothesis of Association: Correlation

For the Spearman r, the null hypothesis states that

A study was done to determine if a correlation exists between age of first arrest and the number of years of education an inmate had. A random sample was selected from the male population of a certain house of correction and their first-arrest ages were tallied along with their years of education. Subj\# Age first arrest Education Years 1 15 8 2 17 9 3 32 12 4 25 11 5 42 16 6 18 11 7 20 10 8 19 9 9 20 11 10 16 10 -What kind of research is this experimental or post-facto?

A researcher wishes to find out whether there is a dependable relationship between the severity of earthquakes and temperature for the 7 days immediately preceding the quake. A sample of 10 measured earthquakes was randomly selected from those recorded since 1965. For each area both the Richter value (higher value meaning more severe quakes) and the mean temperature for the 7 days preceding the quakes were recorded. The data follow: Area Richter Scale Value Mean Temperature A 8.0 65 B 7.0 67 C 4.9 70 D 6.5 66 E 5.0 65 F 5.5 60 G 5.0 63 H 4.5 64 I 5.0 65 J 2.0 65 Neither distribution appears to be skewed. -On the basis of the above data, can the severity of earthquakes be predicted on the basis of previous temperature?

In order to rank-order the following IQ scores, 120, 110, 110, 105, the appropriate ranks would be

The more a correlation deviates from zero,

If rejected, state the significance level.

11-106.For the following ranks, a. Calculate the Spearman r b. Should Ho be rejected or accepted? If rejected, state the significance level. 2.5 2.5 1.0 5.5 7.0 8.0 4.0 5.5 2 1 2 5 7 8 6 4 3

For the following scores, a. Find the Pearson r. b. If Ho is rejected state the level of significance. X Y 12 10 2 3 5 7 9 5 11 9 10 8 4 6 1 3

Questions below will be based on the following: A group of 10 subjects was given a personality test. Among the traits measured on the test were Orderliness and Social Conformity. The scores were as follows: Subject \# Orderliness Social Conformity 1. 9 11 2. 6 8 3. 12 13 4. 7 6 5. 10 10 6. 4 6 7. 9 11 8. 10 9 9. 9 9 10. 2 2 -Was the correlation significant?

For the Pearson r, the alternative hypothesis states that

The Following Questions will be based on the following: A group of 10 college seniors was randomly selected and given a WAIS-III IQ test. The IQs were recorded and then compared with each student's rank in class. The data are as follows: Student\# IQ Rank In Class 1. 120 1 2. 125 2 3. 122 3 4. 110 4 5. 95 5 6. 105 6 7. 100 7 8. 110 8 9. 100 9 10. 94 10 -The class ranks represent which scale of measurement?

The Spearman r is a parametric test of correlation.

A researcher is interested in whether a correlation exists between Alcohol scores and Drug Abuse scores on the MAQ (Maryland Acquisition Questionnaire). A group of inmates, all of whom had at least two previous incarcerations, were given the MAQ and their Drug and Alcohol scores were compared. Subj\# Drug Alcohol 1 34 40 2 75 60 3 48 53 4 55 47 5 40 50 6 42 48 7 56 52 8 44 54 9 54 44 10 52 56 11 48 51 12 50 41 13 47 38 14 53 55 15 60 40 16 40 60 17 48 58 18 52 60 19 50 48 20 53 47 -Is it significant?

The restricted range phenomenon suggests that the value of the correlation between two variables will diminish as the distributions of scores being compared become more homogeneous.

When two sets of measures have been found to be totally independent of each other, then the

Each point on the scatter plot portraying these data would indicate

When Ho is rejected for the Pearson r, then

For any correlation to be considered significant, the null hypothesis must first be rejected.

Significant correlations always predict with an accuracy which is better- than-chance.

Questions below will be based on the following: A group of 10 subjects was given a personality test. Among the traits measured on the test were Orderliness and Social Conformity. The scores were as follows: Subject \# Orderliness Social Conformity 1. 9 11 2. 6 8 3. 12 13 4. 7 6 5. 10 10 6. 4 6 7. 9 11 8. 10 9 9. 9 9 10. 2 2 -Find the linear correlation between the two traits.