Exam 10: The Hypothesis of Difference

The alpha level sets the probability for the

Increasing the sample sizes, increases the probability of incurring the Type 2 error.

A researcher was interested in studying the possible deterrent effect of sentencing. A sample of 12 recidivists was compared with another sample of 12 who had stayed clean. Both groups had been convicted of distributing drugs and both groups had served time. For each subject the length of the previous sentence in months was found. Non-Recidivists Recidivists 36 60 48 72 54 59 32 35 66 56 45 55 37 42 46 57 35 60 42 64 28 97 24 28 -Do the two groups differ significantly?

Whenever the null hypothesis is rejected, then

When selecting a pair of random-sample means from a single population, the probability of the first mean being higher than the second mean is

The independent t ratio specifies how far the difference between the sample means deviated from

A researcher selects a pair of random samples. In Group 1 the scores are 10, 4, 12, 5, 4, 6, 8, 7. In Group 2 the scores are 6, 4, 9, 3, 2, 5, 7, 4. a. Find the t ratio b. As a two-tail t, should Ho be rejected? If rejected, state the probability of the alpha error. c. Do the two groups represent a single population?

A group of 20 violent drug abusers, all of whom had committed homicide while under the influence of a psychostimulant, was selected from the population of a certain prison. Half the men had been cocaine abusers while the other half had been on methamphetamines. All were abstinent at the time of testing. The men were tested on the CAQ (Clinical Analysis Questionnaire) and their Factor Q1 scores were compared (Factor Q1 includes Radicalism, Hypochondriasis and Boredom & Withdrawal). Their scores, converted to T scores, were as follows: Cocaine Group: 65,58,65,62,60,61,70,71,68,75. Methamphetamine Group: 60,53,52,55,54,59,62,60,60,56 -Was this experimental or post-facto research?

When the difference between pairs of randomly selected means are obtained, the resulting distribution is called

For the independent t test, degrees of freedom are based on

For the t ratio, degrees of freedom are based on the number of samples rather than the size of the samples.

A researcher selects a pair of random samples. In Group 1 the scores are 3, 7, 6, 5. In Group 2 the scores are 4, 6, 2, 2. a. Find the t ratio b. As a two-tail t, should Ho be rejected? If rejected, state the probability of the alpha error. c. Do the two groups represent a single population?

A researcher selects a pair of random samples. In Group 1 the scores are 21, 19, 177, 13, 11, 9, 7.In Group 2 the scores are 20, 18, 15, 11, 11, 8,4. a. Find the t ratio b. As a two-tail t, should Ho be rejected? If rejected, state the probability of the alpha error. c. Do the two groups represent a single population?

When the Levene test results in a significant value, .05 or less, then the variances can be assumed to be equal.

The independent t test may be used to evaluate the difference between

The t ratio, since it is a parametric test, makes no assumptions regarding the shape of the population distribution from which the samples have been selected.

The larger the sample sizes, the greater the degrees of freedom.

A researcher was interested in studying the possible deterrent effect of sentencing. A sample of 12 recidivists was compared with another sample of 12 who had stayed clean. Both groups had been convicted of distributing drugs and both groups had served time. For each subject the length of the previous sentence in months was found. Non-Recidivists Recidivists 36 60 48 72 54 59 32 35 66 56 45 55 37 42 46 57 35 60 42 64 28 97 24 28 -Identify the dependent variable.

Like the T score, the t ratio is a measure of

The t distributions deviate from normality when