Statistics Final Study #3

Front 1

T or F? Chi Square Tests are parametric tests.

Back 1

False, Chi Square tests are nonparametric tests.

Front 2

Chi Square Tests do not assume: (2 things)

Back 2

1. interval level of measurement
2. Data are normally distributed

Front 3

What are the 2 types of Chi Square tests?

Back 3

1-way and 2-way

Front 4

What is the purpose of a 1-way Chi Square test?

Back 4

To compare an observed distribution with a hypothesized one. "Goodness-of-fit test"

Front 5

The Chi Square "Goodness-of-fit test" allows you to make this comparison by comparing the _____ frequencies in your sample to the _____ frequencies that you would expect based on the population percentages.

Back 5

Observed, Expected

Front 6

What is the purpose of a 2-way Chi Square test?

Back 6

To see whether two variables are independent of each other or are associated.

Front 7

No relationship in a 2-way Chi Square test looks like what percentages in the table?

Back 7

80% 80%
20% 20%

Front 8

The 2-way Chi Square test of independence tells you what?

Back 8

Whether there is an association (relationship) between type of therapy and outcome.

Front 9

In a 2-way Chi Square test of independence, you could say: did one therapy work better than the other? If not, then type of therapy and outcome are?

Back 9

Independent

Front 10

Sit. where you can use a Chi Square Tests 1 of 5:
Both types of Chi Square tests are based on the difference between _____ frequencies and _____ frequencies.

Back 10

Observed, Expected

Front 11

In a 2-way Chi Square Test, what type of frequencies are expected if there is no relationship between the variables?

Back 11

Expected frequencies

Front 12

Sit. where you can use a Chi Square Tests 2 of 5:
Chi Square Test are used with data in the form of ____ (not scores).

Back 12

Counts

Front 13

Chi Square Tests can be any one of the following types of frequency data? (3 types)

Back 13

Frequency data (f)
Proportions (f/N)
Percentages (proportion X 100)

Front 14

What do you do with proportions and percentages in order to see whether the observed frequencies differ from the expected frequencies?

Back 14

Convert them to frequency data

Front 15

Frequency data conversions:

Back 15

.5 of 100 participants = 50
35% of 100 participants = 35/100 x 100 = 35

Front 16

Sit. where you can use a Chi Square Tests 3 of 5:
The IV in a 1-way and the 2 IV's in a 2-way Chi Square Test must be ____ categories.

Back 16

Discrete

Front 17

In Chi Square Tests, the data must be _____ and the ______ must not overlap.

Back 17

Categorical, categories

Front 18

Sit. where you can use a Chi Square Tests 4 of 5:
Can have a 1-way or a 2-way design. Each IV can have ___ or more levels (i.e., categories)

Back 18

2
Ex. Religion (Prot., Cath., Jew., Other) by Ethnicity (Afr-Am., Asian, Latino, Other)

Front 19

Sit. where you can use a Chi Square Tests 5 of 5:
A participant can only be in ___ cell of the table.

Back 19

1. A participant can not be in more than one group, he can only be in the 2-way table only once.

Front 20

Chi Square Goodness-of-Fit Test (1-way) is appropriate when there is one _____ IV with __ or more levels and the DV is a _____.

Back 20

Nominal, 2, Count

Front 21

The purpose of a Chi Square Goodness-of-Fit Test is to compare an _______ distribution to a ______ distribution or some previously specified distribution.

Back 21

Observed, Theoretical

Front 22

The test statistic that is compared with the table value is the _____ _____ _____ and it provides a measure of how much the observed and expected frequencies ______.

Back 22

Chi Squared Statistic, Differ

Front 23

In a Chi Squared Test, when we compute X-squared and if it is larger than the critical value with (____)df, we _____ the Ho that there is no difference between the observed and expected frequencies.

Back 23

(k - 1)df; reject the Ho

Front 24

Rejecting a Chi Squared Test Ho, means that the _____ data did not come from a ______ with the hypothesized distribution.

Back 24

Sample; Population

Front 25

Chi Squared Test Example:

Back 25

See p.3 of Chi Squared Test handout

Front 26

When you use the Chi Squared Test, you must have expected frequency for each and every category of:

Back 26

5 for df > or = 2
10 for df = 1

Front 27

If you don't have at least this many, you can do one of two things:

Back 27

1. Collapse your groups together to increase the expected frequencies (have few categories). Do this only if the categories created make sense.
2. Take a larger sample.

Front 28

In a Chi Squared Test, when there is only 1 df, ____ correction for ____ should be made.

Back 28

Yates; continuity

Front 29

For a Chi Squared Test of Independence (2-way), you must have ___ _______ IV's, each with __ or more levels, and a DV that is a _______ variable.

Back 29

2, Nominal; 2; Frequency

Front 30

What is a table called with 2 nominal IV's with frequencies in the cells?

Back 30

Contingency Tablle

Front 31

What is the purpose of a Chi Squared Test of Independence?

Back 31

To test whether the 2 IV's are independent of one another.

Front 32

In a Chi Squared Test of Independence, if outcome is independent of type of therapy, you conclude:

Back 32

Outcome is related to type of therapy.

Front 33

Hypothesis testing: in a Chi Squared Test of Independence, generally in the Ho variables A and B are _______ in the population and H1 variables A and B are _______ in the population.

Back 33

Independent; Related

Front 34

To calculate the value of X-squared, you use the same formula as in 1-way. Expected frequencies are calculated differently.

Back 34

See Handout #1 p.5 for E sub rc equation

Front 35

E sub rc equation notation:

Back 35

E sub rc = expected frequency for the cell in row r and cell c
f sub r = frequency for row r
f sub c = frequency for column c
N = total # of observations

Front 36

The expected frequencies are the cell frequencies that would be observed, given the row and column frequencies, if variables A and B were ______.

Back 36

Independent (i.e., not related)

Front 37

What are you really calculating with a Chi Squared Test of Independence?

Back 37

How much the observed frequencies differ from the frequencies that would be expected if the 2 IV's were independent.

Front 38

Conceptually, what is important to notice with a Chi Squared Test of Independence?

Back 38

If the 2 IV's are independent, approximately the same percentage of participants receiving each type of therapy are able to get on the plane.

Front 39

With a Chi Squared Test of Independence if there weren't equal n's in the 2 therapy groups, it would be more useful for purposes of interpretation to look at _____ rather than _____.

Back 39

Percentages; Frequencies

Front 40

When can you not use the Chi Squared Test if Independence?

Back 40

If you find any expected frequency < 5 with df > or = 2, or, < 10 with df = 1

Front 41

If you have a 2 x 2 contingency table, use ____ ____ Test.

Back 41

Fisher's Exact Test

Front 42

When do you need to use Collapsing Levels of a Variable?

Back 42

If it is a larger table, you can use it to increase sample size.
Ex. Can collapse occupation #1 with other occupations if it makes sense to do so.

Front 43

Parametric tests test hypotheses about _____.

Back 43

Parameters

Front 44

Parametric tests involve making the three following assumptions and differ from nonparametric tests assumptions in what way?

Back 44

1. Interval level data
2. Normally distributed
3. Equal variances on the DV in all groups
Nonparametric tests do not assume making any of these assumptions.

Front 45

The two nonparametric tests that we have already covered are 1. ____ and 2. _____, and they are used to examine whether there is a ______ or _____ between two variables.

Back 45

Spearman rank correlation coefficient,
Chi Square Test of Independence;
Relationship, Association

Front 46

An alternative to the independent groups t test that tests whether the central tendency is the same in two groups is:

Back 46

Wilcoxon t test for Two Independent Groups (Mann-Whitney U)

Front 47

How does the data in the Wilcoxon t test for Two Independent Groups differ from the independent groups t test?

Back 47

Independent groups t test data was the scores, Wilcoxon t test for Two Independent Groups (Mann-Whitney U) data are ranks.

Front 48

Steps for using the Wilcoxon t test for Two Independent Groups (Mann-Whitney U) test:

Back 48

1. Convert scores to ranks
2. Write the scores out in order
3. Rank from lowest to highest
4. The computer tells you whether the groups are significantly different in CT and gives you average rank for each group.
5. If the groups are different in CT, the average ranks will be different.

Front 49

When to use the Wilcoxon t test for Two Independent Groups (Mann-Whitney U)?

Back 49

If the assumptions for the t test are not met, i.e., data are not interval level, but ordinal, data are not normally distributed; or variances are unequal.

Front 50

If the t test assumptions are met, why is it better to use a t test than the Wilcoxon t test for Two Independent Groups (Mann-Whitney U)?

Back 50

The t test has more power.

Front 51

There is another test to determine whether two tests have the same median. It is called the _____ _____ and is based on the number of observations ______ and ______ the median.

Back 51

Median Test; above and below

Front 52

What is the test called that is analogous to the dependent samples t test?

Back 52

Wilcoxon t test for Dependent Samples

Front 53

When do you use the Wilcoxon t test for Dependent Samples?

Back 53

It is for comparing the means under 2 treatments. Use when the same participant is observed in 2 treatment conditions (or when you have matched pairs of participants)

Front 54

In the Wilcoxon t test for Dependent Samples, how do you conclude that the 2 populations are different?

Back 54

When the sum of the positive ranks is not equal to the sum ofthe negative ranks.

Front 55

Steps to compute the Wilcoxon t test for Dependent Samples:

Back 55

1. Compute the differences, say pre and post
2. Rank order the differences without regard to sign (remember to average ranks of the same scores)
3. Attach sign of the difference
4. If no difference between the distributions in the two populations (i.e., pre and post), then the sum of the positive ranks should equal the sum of the negative ranks.
5. Conclude there is a difference when, for example, the sum of the positive ranks is much greater than the sum of the negative ranks.

Front 56

What test should you use to test for paired (correlated) dichotomous variables?

Back 56

The McNemar Test
Ex. Success/failure on 2 tests; is there a difference between test 1 and test 2? Participants take both tests.

Front 57

What is the test that is a nonpaframetric alternative to 1-way ANOVA?

Back 57

Kruskal-Wallis 1-way ANOVA by Ranks

Front 58

What does the Kruskal-Wallis 1-way ANOVA by Ranks assume?

Back 58

All data are ordinal (can also be interval).

Front 59

Steps to run the Kruskal-Wallis 1-way ANOVA by Ranks test:

Back 59

1. All scores are rank ordered regardless of group beginning with the lowest score.
2. Then the ranks are summed for each group.

Front 60

In the Kruskal-Wallis 1-way ANOVA by Ranks test, if the results are significant, we conclude what?

Back 60

That the groups differ in their average scores on the DV.

Front 61

You can use the Kruskal-Wallis 1-way ANOVA by Ranks test when: (3 things)

Back 61

1. There is one nominal IV with 2 or more levels
2. The participant is in only one group.
3. The number of people in each group is at least 6.

Front 62

When we get a significant result in the Kruskal-Wallis 1-way ANOVA by Ranks test, we need to use what to see which specific pairs of groups were significantly different on the DV?

Back 62

Pairwise Post Hoc Comparisons to apply the multiple comparison procedure

Front 63

Pairwise Post Hoc Comparisons applies the multiple comparison procedure to:

Back 63

Mean Ranks
(Tukey's HSD procedure compares all possible pairs of means.)

Front 64

In Pairwise Post Hoc Comparisons applies the multiple comparison procedure comparing mean ranks, what do we need to have?

Back 64

Equal n's in the groups

Front 65

What is the equation for the mean rank for one group?

Back 65

The sum of the ranks for the people in that group/the number of people in that group