Exam 10: The Hypothesis of Difference

Anytime the probability of beta is reduced, then

Since psychopaths account for a quarter of all prisoners in the United States (and for as much as 50% of all violent crime) researchers have been examining the personality traits that may play a role in this condition. Tow groups of inmates, half diagnosed by Psychiatrists as psychopathic and the other not so diagnosed were given the IRI (Interpersonal Reactivity Index as a measure of empathy). The scores, converted to T scores were as follows: Psychopaths: 35,40,28,44,45,48,42,38,40,44. Non-Pychopaths: 52,60,50,48,55,50,54,55,44,40. -Was this experimental or post-facto research?

The estimated standard error of difference may be obtained on the basis of the information contained in

The Levene test may only be calculated with nominal data.

The effect size is determined by how much difference there is between the

The Central Limit theorem states that the distribution of differences is

The independent t ratio may be used to evaluate whether

The only time a difference between two sample means may be called "significant" is when

The central limit theorem suggests that the entire distribution of differences between pairs of successively drawn sample means will approximate normality.

The distribution of differences is a distribution of sample measures.

The estimated standard error of difference is an interval estimate of the true mean of the distribution of underlying individual scores.

The t ratio may only be calculated when the data are in ordinal form.

As a one-tail t, since the direction of the difference might have been predicted, do you reject or accept the null hypothesis? If rejected, what is the significance level?

The t distribution assumes normality only when

A researcher selects a pair of random samples and predicts beforehand that Group 1 will score higher than Group 2. The scores in Group 1 are 6, 7, 10, 9, 8. The scores in Group 2 are 3, 4, 9, 7, 5. a. Find the t ratio b. As a one-tail t, should Ho be rejected? If rejected, state the probability of the alpha error. c. Do the two groups represent a single population?

Student's t should only be used when the homogeneity of variance assumption is met.

With an infinite number of degrees of freedom the t distribution assumes normality.

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 -Find the mean sentence for each group.

The assumption of homogeneity of variance can be tested using the Levine Test.

Since psychopaths account for a quarter of all prisoners in the United States (and for as much as 50% of all violent crime) researchers have been examining the personality traits that may play a role in this condition. Tow groups of inmates, half diagnosed by Psychiatrists as psychopathic and the other not so diagnosed were given the IRI (Interpersonal Reactivity Index as a measure of empathy). The scores, converted to T scores were as follows: Psychopaths: 35,40,28,44,45,48,42,38,40,44. Non-Pychopaths: 52,60,50,48,55,50,54,55,44,40. -Identify the independent variable.