Exam 13: Students T Test for Single Samples

The t test is more powerful than the z test.

The 99% confidence interval is defined as _________.

Changing sample size has no effect on power when using the t test.

In a t test, when the size of the sample is increased, the confidence interval _________.

| t crit | for any alpha level is _________ | z crit | for N less than infinity.

Other variables held constant, the larger the size of the difference between and , the larger the size of effect.

Using a = 0.05 2 tail , is it reasonable to assume that the following set of scores could have been randomly drawn from a population with a mean of 74.5? X : 73.0, 72.1, 72.0, 69.1, 70.8

What are the values for the degrees of freedom for samples of the following sizes (assuming one is calculating a t test for a single sample)?

As N gets infinitely large, the critical value of t equals the critical value of z .

For the same set of data, is the 99% confidence interval always larger than the 95% confidence interval? Explain why or why not?

You conduct a single sample experiment to determine if the cingulate cortex is involved in learning tasks involving choice behavior. Twenty-two rats with lesions of the cingulate cortex are tested in a two choice Y-maze with the correct arm of the maze being randomly determined from trial-to-trial. A signal light illuminates the correct arm on each trial. Assume that cingulate cortex lesions do not interfere with reception of the signal light. Previous research with a large number of rats on this task has shown that the mean number of trials learn the task is 15 trials. The results of the experiment show a mean of 18 trials with a standard deviation of 5.8 for the lesioned rats to learn the task.

If r obt is not equal to zero, r cannot equal zero.

Use the data presented in the text, Chapter 7, question 12. In that question, r obt = - 0.69 and N = 10. Using a = 0.05 2 tail , is this a significant value for r obt ?

As the degrees of freedom increase, the t distribution becomes more like the z distribution.

In an independent groups experiment, if we must estimate the population standard deviation to determine the significance of the sample results, the appropriate inference test is the _________.

By definition the degrees of freedom for all statistical tests equals N - 1.

As the df increases, the t distribution _________.

Define degrees of freedom.

If = 50 and s = 6.7:

What are the assumptions underlying the t test for single samples.