Stats

Question 1

Which statistical tests are appropriate for:

• experimental designs
• correlational designs

Answer 1

• t-tests and ANOVA
• correlation or regression

Question 2

Inferential stats address the issue of how….

Answer 2

accurately a sample represents a population

Question 3

What are the 4 main assumptions of parametric tests?

Answer 3

 Independence of observations.
 Interval-or ratio-level data.
 Normal distribution of data.
 Homogeneity of variance

Question 4

What are the 3 ways to handle missing data?

Answer 4

1. Case-wise: deleting the problematic case (respondent)
2. List-wise: deleting the problematic variable
3. Imputation: statistical calculation of what the response may be

Question 5

Hypothesis testing is performed to….

Answer 5

differentiate between real systematic patterns and random chance occurrences

Question 6

What 3 factors affect the probability of making a type 2 error?

Answer 6

1. The sample size (larger N reduces %)
2. The level of significance used for the test (larger alpha reduces %)
3. The actual value of the population parameter (further the true value is from the null values, the smaller the %)

*can control 1 and 2, can’t control 3

Question 7

What two things increase the power of a test?

Answer 7

increase in sample size
increase in difference between the true pop value and the null hypothesis value

Question 8

The standard error provides a measure of….

Answer 8

how much difference is
reasonable to expect between a statistic and a parameter

Question 9

Type 1 errors are ….

Type 2 errors are…

Answer 9

• false positives (finding a sig result when there isn’t one. % = alpha)
• false neg (NOT finding a sig results when there is one. % is hard to know)

Question 10

What 3 things influence the outcome of a test

Answer 10

• size difference between sample mean and original population mean
  (large discrep increase chance of sig res)
• variability of the scores (more var = larger std error)
• number of scores in the sample
  (larger n = smaller std error)

Question 11

What are the 3 measures of effect size?

Answer 11

• Cohen’s d
• Percentage of variance
• Confidence intervals

Question 12

There are key requirements for multiple regression that need to be checker before running an analysis.

Answer 12

There are on the lesson 9 tab

Question 13

In multiple regression models, smaller residuals are associate with…

Answer 13

higher R^2 values and low Sy.x values (standard error estimate/standard deviation of y, given x)

Question 14

APA reporting/interpretation of multiple reg is on

Answer 14

slide 28 of week 9

Question 15

assumptions for mult reg on slide…

Answer 15

47 of week 9

Question 16

One of the assumptions in mult. reg. is that there must not be large degrees of….

Answer 16

multicollinearity

Durbin-Watson test should be between 1.5-2.5
*results closer to 0 or 4 indicates greater degrees of pos and neg autocorrelation than is good

Question 17

VIF scores should be below…. or tolerance above…

Answer 17

4

.25

Question 18

Correcting for violated assumptions on slide…

Answer 18

67 of week 6