Week 4 - Statisitical Models Correlation & T-tests

Question 1

It is critical in psychological research to operationalise key terms because…

Answer 1

The reader needs to know what is actually being studied

Question 2

A normal distribution as a…

Answer 2

Bell shape

Question 3

“It was predicted that individuals who completed more years of education would have lower cardiovascular disease burden”. What is the correct characterisation of this statement?

Answer 3

It is a directional hypothesis.

Question 4

We use the terms independent variable and dependent variable for….

Answer 4

Experimental and quasi-experiential designs

Question 5

We use the terms predictor variable and outcome variable in…

Answer 5

Observational

Question 6

We are running a study manipulating bedroom light levels to investigate effects on sleep efficacy. What is the (1) IV and what is the (2) DV?

Answer 6

(1) bedroom light, (2) sleep efficacy

Question 7

What is not a measure of central tendency?

a.
Skew

b.
Mean

c.
Median

d.
Mode

Answer 7

Skew

Question 8

Leptokurtic means…

Answer 8

Positive kurtosis

Question 9

Negative kurtosis is also …

Answer 9

Platykurtic

Question 10

Normal distribution is also

Answer 10

Mesokurtic

Question 11

when do we run a Spearman Correlation?

Answer 11

When the data is non parametric

Question 12

When do we run a Wilcoxin test (as opposed to a t-tes)

Answer 12

when the DV is non paramtertic

Question 13

We traditionally use cohens d to measure effec size for t-tests. True or False

Answer 13

True

Question 14

a d-value of 0.2 is considered…

Answer 14

small effect

Question 15

a d-value of 0.5 is considered…

Answer 15

moderate effect

Question 16

a d-value of 0.8 is considered…

Answer 16

large effect

Question 17

Testing skew or kurtosis:
W statistic - maximum value of 1 = data looks perfectly normal
True or False

Answer 17

True

Question 18

Testing skew or kurtosis:
The smaller the value of W the less normal the data are?
True or false

Answer 18

True

Question 19

p value of W statistic
<.05 = non normal data
True or false

Answer 19

True

Question 20

p value of W statistic
>.05 = normal data
True or false

Answer 20

True

Question 21

p value of W statistic
>.05 = non normal data
True or false

Question 22

the higher the df = more statistical power
True or False

Answer 22

True

Question 23

df = participants - 1
True or false

Answer 23

True

Question 24

What are the assumptions of Pearson correlation?

Answer 24

Linear relationship (straight line).
Homogeneity of variance (homoscedasticity).
Parametric data/normality.
Independence.
At least one variable needs to be continuous.
The other variable can be continuous or dichotomous.

Question 25

What are assumptions of t-tests?

Answer 25

Parametric data/normality.
Independence.
Homogeneity of variance (homoscedasticity).
DV needs to be continuous.
IV needs to be dichotomous (groups or time points

Question 26

Pearson correlation
r= 0 no relationship
r=1 perfect positive relationship
R -1 perfect negative relationship
True or False

Answer 26

True

Question 27

Pearson correlation also measures effect size
-1.0 to- 0.9 is a very strong negative correlation
-0.9 to -0.7 strong neg
-0.7 to -0.4 moderate neg
-0.4 to -0.2 is a weak negative correlation
-0.7 to -0.4 is moderate negative

0 - 0.2 is a negligible positive
0.2 to 0.4 is a weak positive correlation
0.4 to 0.7 Moderate pos
0.7 to 0.9 is a strong pos
0.9 to 1.0 is a very strong positive correlation

Answer 27

True

Question 28

Why do we use t-test

Answer 28

When you want to compare two means

Question 29

When do we use between independent t-test?

Answer 29

If those two means are from different groups - assigned to 1 condition only
i.e., group 1 vs group 2

Question 30

When do we use within groups dependent/paired t-test?

Answer 30

if those two means are from the same people - assigned to both conditions
i.e., time 1 vs time 2 using the same groups to compare

Question 31

Parametric data (normal)
Bell curve
Not too skewed (sway left or right)
Not too kurtotic (flat or peaky)
No outliers (extreme values)
T or F

Answer 31

True