Exam 11: The Hypothesis of Association: Correlation

The more any correlation value deviates from zero

On a scatter plot, the ordinate is used to represent

A researcher wishes to test the hypothesis that there is a correlation between IQ and math ability. A random sample of 8 subjects was selected. Each subject was given an IQ test, and then rank-ordered in terms of mathematical ability. IQ Score Math Rank 130 1 92 5 115 4 115 3 82 6 82 7 60 8 120 2 -Calculate the appropriate correlation.

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. -Should Ho be rejected or accepted?

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 IQ scores represent which scale of measurement?

Among elementary school children, the correlation between age and height would most probably be

For the following ranks, calculate the Spearman r_s R1 4.0 8.5 6.0 1.0 2.5 2.5 6.0 8.5 6.0 10.0 2 5 4 3 1 2 6 8 7 9 10

A maximum linear correlation is expressed as

The Spearman r is to ordinal data as the Pearson r is to interval data.

The reason for the typical shape assumed by the array of points in a scatter plot, is due to

A researcher wishes to test the hypothesis that there is a correlation between IQ and math ability. A random sample of 8 subjects was selected. Each subject was given an IQ test, and then rank-ordered in terms of mathematical ability. IQ Score Math Rank 130 1 92 5 115 4 115 3 82 6 82 7 60 8 120 2 -Should Ho be rejected or accepted? If rejected, state the level of significance.

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 -What kind of research is this experimental or post-facto?

A researcher has computed two significant Pearson r values from independent random samples. Sample A, 171 subjects, produced an r of .75 and Sample B, 175 subjects, produced an r of .60. Do the two sample correlations represent a common population correlation?

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 -Find the Mean for each set of scores.

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 -What conclusions might you draw?

For the Pearson r, when Ho is rejected, it means that

Questions below are based on the following. A group of 10 college sophomores was randomly selected and given a personality test that measured both orderliness and rebelliousness. The scores were as follows: Subject \# Orderliness Rebelliousness 1. 9 6 2. 6 8 3. 12 2 4. 7 6 5. 10 10 6. 4 11 7. 9 11 8. 10 9 9. 9 9 10. 2 13 -Find the linear correlation between the two traits.

A researcher is interested in testing the hypothesis that income is negatively related to family size. A random sample of 10 families was selected from the population of a large mid-western city. All families were assessed on both their per-family income and their numbers of children Family Per-family income Number of children A \ 190,000 2 B \ 30,000 6 C \ 19,000 7 D \ 40,000 3 E \ 23,000 6 F \ 40,000 4 G \ 25,000 5 H \ 40,000 3 I \ 28,000 1 J \ 30,000 5 Since the income distribution was badly skewed, it was decided not to use the Pearson r. -Calculate the appropriate correlation

To calculate the degrees of freedom for the Spearman r, one must

11-89.The Pearson r is a non-parametric test of correlation.