Lecture 13 Flashcards

1
Q

One Factor ANOVA is used to test for?

A

Differences in the means of 3 or more populations

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2
Q

What type of data does the one-factor ANOVA use?

A

Ratio-interval scale data

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3
Q

What assumptions of one-factor ANOVA does it require?

A

To follow a NORMAL distribution and have equal variances

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4
Q

What is the response variable in ANOVA?

A

(Dependent variable) the ratio-interval scale variable that you are actually measuring

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5
Q

What are factors in ANOVA?

A

(Independent variable) the nominal scale variable that will group the data into categories

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6
Q

What defines the type of ANOVA?

A

The factors

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7
Q

What are levels in ANOVA?

A

(Groups, type of treatments, or sample) the CATEGORIES themselves contained within the factors

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8
Q

What is the null hyposthesis in One-factor ANOVA?

A

All the means of each population are equal

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9
Q

What is the alternative hyposthesis in one-factor ANOVA?

A

At least one population mean is different

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10
Q

What does k stand for?

A

The number of populations

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11
Q

What does X-double bar, N, and G stand for?

A

The grand mean, grand sample size, and grand total

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12
Q

What is similar to ANOVA?

A

Two sample t-test

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13
Q

what can be used to test for normality for ANOVA?

A

D’Agostino Pearson k^2 test

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14
Q

What can be used to test for homoscedascity in ANOVA?

A

Bartlett’s test and Levene’s test

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15
Q

Why is a test that looks at differences in the means of three or more populations called analysis of variances?

A

The analysis of variances explains the different sources of variation in the data

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16
Q

What are the three variations One-factor ANOVA?

A

Level variation, error variation, and total variation

17
Q

What is level variation?

A

The variation among the levels (groups/treatments) of a given factor

18
Q

What is error variation?

A

The “within” group (level) variation that is unexplained

19
Q

What is the total variation

A

The combination of the “among” group and “within” group variations

20
Q

What is the test statistic calculated in ANOVA?

A

ONE TAILED F-test, like variance ratio test

21
Q

What are the two variances of interest in the one-factor ANOVA?

A

The among-group variances and within-group variances

22
Q

Why is there just one within-groups variance value if there are 3 or more groups?

A

Due to the equal variance assumption being true would be all the same within each group

23
Q

Which variance goes in the numerator and denominator?

A

Numerator = among group variance, denominator = within-group variance

24
Q

What must be the case in order to reject the null hypothesis and conclude that there is a difference among the means of the groups?

A

The among-group variation must be greater than the within group variation

25
Q

Why is it important for the among-group to have a larger fraction of the total variation than the within-group?

A

In order to explain that the source of variation is due to the among group variation rather than unexplained reasons (error variation)

26
Q

Why is the among group variance in the numerator?

A

It is expected to be larger than the within-group variation

27
Q

Why is ANOVA one tailed?

A

There is an expectation as to direction (among > within)

28
Q

What are variances referred to as in ANOVA tests?

A

Mean squares (MS)

29
Q

Why calculate MSTOT if the total variation is not needed in the calculation of F?

A

Just in case for other calculations

30
Q

Between mean squares, sum squares, and degrees of freedom, which are additive and which are not?

A

SS and DF = additive, MS = not additive

31
Q

what is included in the ANOVA table?

A

Sources of variation, sums of squares, degrees of freedom, mean squares

32
Q

What is Model I ANOVA

A

Fixed-effects, includes all of the levels that you are interested in

33
Q

What is Model II ANOVA?

A

Random-effects, levels chosen are randomly selected from a large set of levels

34
Q

How to determine which population mean is different? (2 ways)

A

Incorrect method and correct method

35
Q

What is the incorrect method?

A

Multiple t-tests

36
Q

What is the correct method?

A

Multiple comparison (Tukey test) test following up to an one-factor ANOVA

37
Q

What nonparametric alternative is used if normality and homoscedasity requirements are not met?

A

Krustal-Wallis Test (ranking)