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Flashcards in Stats 2 Second Exam Deck (21)
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1
Q

2 (or more)-way ANOVA is used when one has…

A

2 or more fixed categorical IVs and 1 or more continuous random DV

2
Q

2-way ANOVA hopes to find

A
  1. Interactions 2. Main effects
3
Q

“2 way ANOVA” indicates _____ whereas “2 x 2 ANOVA” indicates

A
  1. That we have 2 IVs 2. That we have 2 IVs, each with 2 levels.
4
Q

What does “Factorial design” mean?

A

More than one IV

5
Q

What is the goal of 2-way ANOVA?

A

Add second IV that strengthens first IV and reduces E

6
Q

What is an interaction?

A

Second IV affects the levels of 1st IV differently

7
Q

How can one examine interaction graphically?

A
  1. Parallel lines means there is no interaction
  2. Test of interaction is test of parallelism. Not testing if means are significantly different
  3. Examination of slope (how regression works)
8
Q

What should one do statistically upon finding a significant interaction?

A

Do not pursue main effects.

9
Q

What are the 3 hypotheses of 2-way ANOVA?

A
  1. Interaction 2. Main effect A 3. Main effect B
10
Q

What is the effect of adding a 2nd IV on power?

A
  1. Doubles number of participants one needs to have in order to achieve sufficient power
  2. Because power is based on cells– the smallest breakout that one will compare
11
Q

What questions does one ask in 2-way ANOVA?

A
  1. Is there a significant effect? 2. Where is it? 3. How big is it?
12
Q

What are assumptions of 2-way ANOVA?

A
  1. n 4:1 ratio
  2. N - Normality of error term (not normal distribution of subjects). Error term = that for which is not accounted.
  3. I - Independence - participants can be in only 1 cell at a time. Cannot randomly assign to a tx group and then a second tx group.
  4. H - Homogeneity - Equivalent variances (SDs) of all cells. Across IVs and also across interactions
  5. R - Random
13
Q

What does ATI stand for?

A

Attribute-Treatment Interaction

14
Q

What is Attribute-Treatment Interaction?

A
  • Uses both experimental and ex post facto methods:
  • Treatment-Control = experimental variable
  • M/F or SES = organismic variable
  • Can manipulate one variable but not the other.
15
Q

How is Attribute-Treatment Interaction conducted?

A
  • Randomly assign to treatment (experimental variable).
  • Randomly select from attribute (organismic variable).
  • May have control and treatment or multiple treatments
  • May have control organismic variable.
  • Main objective is to assess interaction.
16
Q

What does it mean when lines of interaction graph cross?

A
  1. There is an interaction effect. 2. Termed “Disordinal Interaction”
17
Q

What does it mean when lines of interaction graph change slope but do not cross?

A
  1. There is an interaction effect. 2. Termed “Ordinal Interaction”
18
Q

What does it mean when lines of interaction graph are parallel?

A

No interaction

19
Q

Interaction hypothesis is addresses through

A

Graphing

20
Q

Main effect hypotheses are addressed through

A

Post-hoc tests (if interaction is not demonstrated)

21
Q

What is included in 2-way ANOVA source table?

A
  • Source SS df MS F
  • IV (by name)
  • IV 2 (by name)
  • Interaction
  • Error
  • Total