W10

Question 1

independent samples t tes

Answer 1

• the two groups being used are not related in any form (independent)

Question 2

independent samples t test assumptions

Answer 2

1) amount of variability in each of the groups is equal -> homogeneity of variance, sameness
2) both groups show a normal distribution or N>30 for both groups
3) IV is categorical and consisting of 2 groups
4) DV is measured at interval or ratio level
6) sample is random

Question 3

degrees of freedom

Answer 3

approximates the sample size
- If the obtained value is more extreme than the critical value (0.05), the H0 is rejected
- if the obtained value does not exceed the critical value (0.05), the H0 is retained

Question 4

effect size

Answer 4

measure of how strongly variables relate to one another, with group comparisons, its a measure of the magnitud of the difference

cohens D:
- 0.2 - small
- 0.5 medium
- 0.8 large

Question 5

p value

Answer 5

significance
- likelihood of rejecting the hypothesis when is true is low or high
example: p = 0.89
likelihood of rejecting the hypothesis when it is true is high (89/100)

Question 6

t test for dependent means (paired samples)

Answer 6

indicates that a same sample is being studied under two conditions (e.g. before the start of the experiment and after its conditions)

dependent means - pretest posttest

Question 7

paired samples t test assumptions

Answer 7

1) paired observations - each participant or init must have two related measurements
2) normal distribución N>30
3) scale of measurement - dependent variable should be measured on a continuous scale (interval or ratio)

Question 8

type 1 error

Answer 8

occurs when a test indicates that there is a difference or effect when in reality there is not

Question 9

p value < 0.05

Answer 9

reject H0
sufficient evidence to support Ha

Question 10

p value > 0.05

Answer 10

Retain H0
not sufficient evidence to prove that an effect occurs (Ha)

Question 11

one way anova

Answer 11

compare the means of 3+ samples of 1 categorical IV and 1 continuous DV

Question 12

complex type of anova

Answer 12

used to explore more than one iv
these factorial designs follow the same basic logic and principles of one way anova, but they can test the influence of more than one factor at a time as well as a combination of factors

Question 13

f-test

Answer 13

one way anova involves testing the difference between the means of more than 2 groups on one factor or dimension

Question 14

levenes test for equality of variance (f test)

Answer 14

• we want to find out if two groups have equal variances
  ONLY test in which you DONT WANT significant results
• we want VARIANCE
• variance - how much individual data points within a single group vary from the groups mean
• goal KEEP H0

1) look at p- value
- if p>0.05:
NOT SIGNIFICANT
equal variances assumed
look at results in the first row, we CANNOT reject H0 (keep. Goal)

2)
- If p<0.05:
SIGNIFICANT
equal variances not assumed
look at results in the bottom row
reject H0

Question 15

when use one way anova

Answer 15

• when there is only one dimension or treatment
• when there are more than 2 levels of the grouping factor and one is looking at the mean differences across groups

Question 16

f ratio

Answer 16

• ratio of the variability between groups to the variability within groups
• compute sum of squares for each source of variability between groups, within groups and the total
• between groups sum of squares = sum of the differences between the mean of all scores and the mean of each groups score which is then squared

within group sum of squares = sum of differences between the mean of all scores and the mean of each groups score which is then squared

Question 17

two way ANOVA

Answer 17

compare the means of 2+ samples of 2 categorical IV and 1 continuous DV

Example: Testing how teaching method (Factor A: A, B, C) and classroom size (Factor B: Small, Large) influence test scores.
- you have 1 dependent variable which is continuous (height, weight)

Question 18

one way ANOVA assumptions

Answer 18

1) normal distribution or N>30 per group
2) IV is categorical and has more than 2 independent groups
3) dependent variable is at least interval
4) groups are approximate equal size
- if they do not have equal size, we look for equal variances (levees test)

NOT SIGNIFICANT = EQUAL VARIANCES
SIGNIFICANT = NOT EQUAL VARIANCES

Question 19

ANOVA variances

Answer 19

within group variances - individuals differ from each other (NOT GOOD)

we want between group variance to be BIGGER than within group variance

Question 20

APA REFERENCE for ANOVA

Answer 20

F(df1,df2) = F, p

Question 21

F distribution

Answer 21

region of rejection for F = 3
F value is bigger than 3, the test is significant