Exam 11: The Hypothesis of Association: Correlation

When the knowledge of one event allows for the prediction of another event, then the two events are

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. -If rejected, state the level of significance.

For the Pearson r, the null hypothesis states that

The correlation coefficient, in and of itself,

The most common error in interpreting correlational research studies is in

The proportion of the variability in the Y distribution which is accounted for by the variability in the X distribution, is determined by

If the researcher uses these data to predict GPA, then the scatter plot's ordinate would represent

A scatter plot on which the array of points goes from upper left to lower right, indicates

In order to make better-than-chance predictions, the Pearson r must be

On a scatter plot, the ordinate should always displays the measures from the Y distribution.

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 -Find the Pearson r between Drug and Alcohol scores

The value of the Pearson r indicates

When the underlying distribution of interval scores is violently skewed, the appropriate correlational technique should be

The major reason for using the correlational techniques is to

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 Pearson r between Drug and Alcohol scores.

Regardless of the degrees of freedom, any Pearson r of .90 or higher must be

Whenever a correlation coefficient deviates significantly from zero, then

With 5 degrees of freedom, the critical tabled value of the Pearson r is .75 for an .05 alpha level. If one were to obtain a Pearson r value of -.76, then

The correlation between parental income and the amount of financial aid awarded by the college to students should most probably be

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 your statistical decision, which error, Type 1 or Type 2 might you have committed?