Test Statistics

Question 1

What is the critical value for the test statistics?

Answer 1

it is the threshold that her test statistic will need to surpass in order to reject the null hypothesis at a certain level of significance

Question 2

What is a type I error?

Answer 2

When the null hypothesis is falsely rejected

Question 3

What is a type II error?

Answer 3

When a false null hypothesis is not rejected

Question 4

How is the probability of failing to reject a false null hypothesis measured?

Answer 4

Beta

Question 5

The Probability of correctly rejecting a false null hypothesis

Answer 5

1 - Beta; the Power of a Test

Question 6

What is the Power of a test

Answer 6

1 - Beta; the probability of correctly rejecting the false null hypothesis

Question 7

The Rejection of a true null is measured by…?

Answer 7

Alpha; i.e. the level of significance

Question 8

When are nonparametric tests appropriate?

Answer 8

1. When data fails to meet distributional assumptions
2. When data are given in ranks
3. when the hypothesis simply doesn’t concern a parameter

Question 9

Nonparametric test used for correlations of two series when one or both of the series are in ranks

Answer 9

The Spearman Rank Correlation Coefficient

Question 10

How can samples of population variances that are not normally distributed be used for Hypothesis tests?

Answer 10

If the data are lognormally distributed and the log values for the data are used

Question 11

When its okay to use z-statistic for a t-test

Answer 11

When the population standard deviation is known (and assuming it is normally distributed)

Question 12

When to use t-statistic over the z-statistic

Answer 12

When the sample is large enough to be normally distributed, but the population standard deviation is unknown

Question 13

Reason why z-statistic is easier than t-statistic

Answer 13

The critical values can be memorized since they are independent of the sample size and therefore do not change

Question 14

What the critical values for a two-tailed z-test with 1%, 5%, and 10% significance levels?

Answer 14

two-tailed @ 1% level = -2.575 and 2.757
two-tailed @ 5% level = -1.96 and 1.96
two-tailed @ 10% level = -1.645 and 1.645

Question 15

What are the critical values for a one-tailed z-test with 1%, 5%, and 10% significance levels?

Answer 15

one-tailed @ 1% = -2.33 and 2.33
one-tailed @ 5% = -1.645 and 1.645
one-tailed @ 10% = -1.28 and 1.28

Question 16

What is the relationship between the t-statistic and the z-statistic as the sample size gets larger?

Answer 16

the t-distribution converges toward the z-distribution; therefore the t-statistic converges toward the z-statistic

Question 17

When should should a pooled variance be used?

Answer 17

When measuring the differences between two means in independent samples.

Question 18

What is the t-test for mean differences most appropriate for examining?

Answer 18

dependent samples, as in before and after measurements

Question 19

What is the test statistic that tests the equality of two variances, and how do you calculate it?

Answer 19

F-statistic; Divide the two variances into each other

Question 20

how do you solve for the chi square test statistic?

Answer 20

n-1 times the sample variance over the hypothesized variance

Question 21

What does a chi-squared test examine?

Answer 21

chi-squared tests examine claims about a population standard deviation or, equivalently, a population variance; it is the correct distribution to use when testing a normally distributed variance