Professor HoltPSYC 340: Statistics II Chi-Square Class Activity [Type text][Type text][Type text]

Professor HoltPSYC 340: Statistics II

Chi-Square Class Activity

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The use of the polygraph for lie detection remains controversial. In a typical laboratory experiment to test the technique, half the subjects are told to commit a mock crime; the other half of the subjects remains “innocent.” The polygrapher, blind to each subject’s condition, must make a judgment of guilt or innocence based on a subject’s physiological responses to a series of questions.

Test the null hypothesis that the polygrapher’s judgments are unrelated to the subject’s guilt.

Fill in the sums, and add your calculated expected frequencies in (parentheses) next to its observed value in the contingency table

Please remember to use complete sentences

Innocent

Guilty

Sums

Judged innocent

10

3

Judged guilty

5

12

Sums

State the hypotheses

.

.

Select the statistical test and significance level

.

.

Describe the sample

.

Find region of rejection (degrees of freedom and chi-sq critical value)

df

Chi-sq crit=

Calculate the TS

fe

2

Decision

.

Interpretation