Exam 10: The Hypothesis of Difference

For the independent t test, the null hypothesis is always stated in terms of

When there is a failure to reject Ho then one may assume that the two sample groups represent a common population.

The statement that the difference between the two population means is zero, represents

Student's t test for two independent samples assumes that the variances within each of the two groups are NOT significantly different from each other.

The mean of the distribution of differences becomes zero only when all sample pairs represent different populations.

In order to ensure a sampling error of zero, each sample must

When the direction of the difference between two sample means is not specified, we must use the two-tail t.

When the null hypothesis is rejected, then the alternative hypothesis must be accepted.

What is the meaning of the negative t ratio?

The larger the effect size, the greater the likelihood

The estimated standard error of difference is an estimate of the variability occurring within the entire distribution of differences.

For the independent t test, the null hypothesis is always

When homogeneity of variance is assumed, then the Levene test will NOT be significant,

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. -Do the two groups differ significantly?

A researcher selects a pair of random samples. In Group 1 the scores are 9, 12, 7, 8, 6. In Group 2 the scores are 6, 5, 7, 6, 5. Find the t ratio.

When all the possible pairs of random sample means have been selected from the population, the mean of the sampling distribution of differences is a parameter.

The estimated standard error of difference estimates the value of the population mean.

Student's t can only be used with nominal data.

The power of a statistical test, such as the independent t test, can be increased by

The t ratio assumes that the two samples being compared are similar with respect to variability.