Lecture 6 Flashcards

1
Q

Which test compares 2 means and only has 1 IV?

A

t-test

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2
Q

Which test compares 3+ means and can be used when you have manipulated more than one IV?

A

ANOVA or “factorial!”

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3
Q

When I use a lot of t-tests to compare several means, this inflates the ______

A

alpha
OR
Type 1 Error Rate

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4
Q

What is another name for ANOVA test?

A

Omnibus test

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5
Q

What does ANOVA do?

A
  • tests for overall difference
  • tells us that means are different
  • doesn’t tell us exactly which means differ
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6
Q

What is an “overall test” that tests a number of different comparisons at once?

A

Omnibus

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7
Q

What question does ANOVA test?

A

Is there a difference somewhere?

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8
Q

What is the SS?

A

sum of squares or total amount of variance

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9
Q

What is the MS equation?

A

MS = Mean Square
MS = SS/df

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10
Q

F = ?

A

MS (between) / MS (within)

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11
Q

Why do we use follow-up tests?

A

Omnibus tells us that there IS a difference among the means, not WHERE

Follow up tests tell us WHERE the group differences lie

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12
Q

What is a planned contrast (follow up) test?

A
  • Has statistical advantage
  • Type of contrasts are limited
  • Needs to be planned a priori
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13
Q

What is a post hoc comparison (follow up) test?

A
  • MOST common
  • not planned
  • compares ALL pairs of means
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14
Q

What is a pairwise test?

A

Typically after global test & implies ONLY 2 means

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15
Q

What is simple effects?

A

run this after global test & significant interaction

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16
Q

Which tests can we use if there are only (1) small deviations from normality, (2) sample sizes in each cell are equal, and (3) variances are homogenous?

A

Bonferroni & Tukey

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17
Q

Which tests are conservative and controls for type 1 error?

A

Bonferroni & Tukey

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18
Q

Bonferroni has more power than Tukey if ______

A

number of comparisons are small

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19
Q

Tukey has more power than Bonferroni if _____

A

the number of comparisons are large

and more power than Dunn and Scheffe

20
Q

Which test do you use if variances are not homogenous?

A

Games-Howell

21
Q

What is the Games-Howell?

A

Powerful but can be liberal when sample sizes are small. Accurate with unequal sample sizes

22
Q

What is the Kruskal-Wallis Test?

A

The non-parametric equivalent to an independent one-way ANOVA

  • select if your data doesn’t meet assumptions
  • Mann-Whitney U tests
23
Q

What is the HOV assumption equivalent in ANOVA called?

A

Sphericity

24
Q

What is the sphericity assumption?

A

The variances of the differences between all possible pairs of groups are equal

25
What is the test for sphericity called?
Mauchley’s test
26
When you have F(2,10) = 12.5, what does the 1st number mean? what does the 2nd number mean?
1st number: # of groups 2nd number: # of participants per group
27
What is Friedman's ANOVA?
non-parametric equivalent of RM - one-way ANOVA
28
What is the difference between a two-way independent ANOVA vs. a factorial ANOVA analysis?
2-way independent ANOVA has 2 IV's factorial ANOVA has 1 IV
29
What does "interaction" look for?
Interesting relationships between the independent variables
30
T/F: If the interaction is significant, don't worry about the main effects.
True
31
If the interaction lines are parallel, is it significant?
No
32
When the interaction is significant, you can run ___ ____
simple effects
33
If **main effect(s)** is significant and interaction is NOT significant, you should run ________
Follow-up main effect pairwise comparisons & report. Adjust alpha level! Note: if only 2 levels for main effect, no follow-up testing needed
34
If **main effect(s)** is significant AND interaction is significant, you should run _____
Simple effects and "forget about" main effects. Adjust alpha level!
35
When do you run simple effects?
If you have a significant interaction!
36
If I am studying self-perceived preparedness in Dental students. I have 3 independent variables and 1 dependent variable. What type of test should I run?
Split/Mixed 3-way Factorial ANOVA
37
If I am studying self-perceived preparedness in Dental students. I have 3 independent variables and 1 dependent variable. How many main effects? How many 2-way interactions? How many 3-way interactions?
3 Main Effects 3 2-way Interactions 1 3-way Interaction
38
What is a covariate?
A variable that is complementary or related to the dependent variable; **extraneous** variable
39
When would you test for covariates?
Test differences between group means when we know that an extraneous/confounding variable can **affect the outcome variable**
40
WHY would you test for covariates?
To strengthen your analysis More likely to find significance if you can identify the covariate and measure it beforehand
41
What is ANCOVA?
analysis of covariance *run analysis on the adjusted means*
42
What is MANOVA?
Multivariate analysis of variance
43
When do you use MANOVA?
To test for differences between groups when we have **several DVs**
44
Why is MANOVA better than multiple ANOVAs?
* controls familywise error rate (Type 1 error) Note: takes into account relationship between the DVs; more powerful than separate ANOVAs **DVs are mathematically combined into aggregate turning it into one variable for the global**
45
What's the next step after a significant Global MANOVA?
DFA (Discriminant function analysis)
46
What is DFA (Discriminant function analysis) used for?
Used to determine which of the DVs are best at discriminating the groups