Exam 10: The Hypothesis of Difference

The t test for two independent samples may only be used when

The t ratio should only be calculated when the data are in at least interval form.

The distribution of differences is

When graphing the distribution of differences, the abscissa is used to represent

The alternative hypothesis for the independent t test is also called

Regarding the distribution of differences, the assumption of normality is based on

The population effect size is estimated in the numerator of the t ratio.

A powerful test is one that is

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 -Was this experimental or post-facto research?

When all samples are drawn from a single population, the mean of the distribution of differences should approximate

With one degree of freedom, a significant t ratio will occur

To do a one-tail t test, as opposed to a two-tail,

The distribution of differences is composed of the differences between

The estimated standard deviation of the distribution of differences is used to predict the

The greater the number of degrees of freedom for the t ratio, the less the likelihood of rejecting the null hypothesis.

The difference between the T score and the t ratio is that

In order to calculate the estimated standard error of difference, all that need be known is (are)

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 -Identify the independent variable.

For questions below, use the following: A researcher wonders if students will spend more time studying for a quiz if they are told that a high mark on that quiz will excuse them from writing a term paper. Two groups of college students were randomly selected from a large lecture course in art history. The students in Group 1 were simply told that they would have their first art-history quiz two days later. In Group 2, they were told the same thing, except that the promise of "no term paper" for high quiz performance was added. Just before taking the quiz, all students in both groups reported (in hours) the time they had spent preparing. In Group 1, the times were 6, 4, 9, 3, 2, 5, 7, 4, 7, 6. In Group 2 the times were 12, 5, 13, 5, 5, 7, 9, 6, 9, 6. -Calculate the means for each group

With infinite sample sizes, t ratios of +1.96