W9: Data Analysis III

Question 1

What is the F ratio in an ANOVA test statistic?

Answer 1

F compares 2 estimates of variability (between and within )

Question 2

What does ANOVA examine?

Answer 2

variability of samples

Question 3

When is Vb greater than Vw (ANOVA table)?

Answer 3

if there is a significant difference between groups

Question 4

The larger the F value, the greater the ratio between __ to __?

Answer 4

the greater the ratio between Vb to Vw; higher F means lower P

Question 5

What is the F distribution used for?

Answer 5

to test hypotheses about population variances; defined mathematically (and theoretically based)

Question 6

Do people of different age groups differ in number of hours of TV watched per day?
F = 8.903 at p< 0.001
Accept or reject null hypothesis?
Conclusion?

Answer 6

reject null hypothesis
Conclusion: there is a difference between age groups for TV hours watched

Question 7

What is a post hoc test? When is it used?

Answer 7

tells you which variables are different from one another.
Used only when p<0.05 because difference is confirmed

Question 8

What are the different types of post hoc tests?

Answer 8

Bonferroni, Tukis, Duncan (unreliable)

Question 9

What is the simplest type of regression?

Answer 9

multiple linear regression- calculate slope and add additional variables

Question 10

What is the 3 M approach?

Answer 10

model, measurement, method

Question 11

What is the limitation of ANOVA?

Answer 11

F does not pinpoint which means are significantly different from each other

Question 12

What are the limitations of ANOVA?

Answer 12

F does not pinpoint which means are significantly different from each other
need post hoc multiple comparison procedure

Question 13

When is a post hoc multiple comparison procedure not needed?

Answer 13

when the F is not significant

Question 14

What is a two way ANOVA?

Answer 14

extension of one way ANOVA, 2 simultaneous IVs of 2+ categories each (nominal/ordinal IV), 1DV (ratio)

Question 15

what is an MANOVA?

Answer 15

multivariate analysis of variance; extension of ANOVA with 2+ DVs

Question 16

(post hoc) If a significant main effect or interaction is found, then you can only conclude that there is…

Answer 16

a significant difference amongst levels of IVs somewhere

Question 17

What is a bivariate correlation?

Answer 17

describes how closely 2 ratio level variables co-vary together

Question 18

what is the difference between bivariate correlations and multiple regression?

Answer 18

bivariate-> analysis of 2 ratio level variables
multiple regression-> analysis of more than 2 ratio level variables (many variables analyzed together)

Question 19

What can bivariate correlations and multiple regressions do in relation to causal relationships?

Answer 19

cannot prove causal relationships but can provide evidence to support causal arguments

Question 20

When is multiple regression used?

Answer 20

to examine impact of several independent variables on dependent variable
- in applied research

Question 21

Give an example scenario when multiple regression is used

Answer 21

to predict how long a senior stays in hospital post-surgery, you might consider many possible predictors (age, severity of illness, physical function scores, depression scores)

Question 22

What is the difference between multiple nonlinear regression vs. multiple linear regression?

Answer 22

nonlinear fits variables on a best fitting “curve”
linear fits variables on best fitting line

Question 23

What makes multiple linear regression a powerful tool?

Answer 23

-isolates separate effects of IVs on DV
-estimates which IV is strongest predictor of DV
-identifies math equation describing linear relationship between IVs and DV

Question 24

What happens during the “Model” of 3Ms?

Answer 24

• determine which variable will be treated as DV and which will be treated as IVs
• specify greater than and less than relationships between variables

Question 25

What happens during the “Measurement” of 3Ms?

Answer 25

identify level of measurement (nominal, ordinal, ratio) for reach variable

Question 26

What happens during the “Method” of 3Ms?

Answer 26

determine which method (stat procedure) appropriate for examining relationships between variables
eg. Crosstabs (chi-square)
means (ANOVA)
correlations