Basic stats knowledge

Question 1

Correlational research: pros and cons

Answer 1

Pros: Ecological validity
Cons: Not good for causality

Question 2

Experimental research: pros and cons

Answer 2

Pros: Good causality (because IV manipulated)
Cons: Not always ecologically valid

Question 3

Parameter

Answer 3

Value that describes the population (e.g. SD, mean…)

Question 4

Describe the place of the median vs mean if: left skewed, right skewed or symmetrical

Answer 4

Left skewed (-): mean < median
Symmetrical: mean = median.
Right skewed (+): mean > median

Question 5

Range formula

Answer 5

X largest - X lowest

Question 6

What’s the fundamental difference between z-test and t-test?

Answer 6

z-test: SD pop known.
t-test: SD pop not known.
-> But sample SD & mean + population mean.

Question 7

p-value

Answer 7

Proportion of data sets that would yield a result AS extreme or MORE extreme than the observed result IF H0 IS TRUE.

Question 8

if p < alpha, what do we do?

Answer 8

Reject H0

Question 9

if p > alpha, what do we do?

Answer 9

Retain H0

Question 10

Confidence interval definition

Answer 10

If we repeat our experiment many times, 95% of the time, our CI will contain the population mean.

Question 11

As alpha decrease, what happens to our confidence interval?

Answer 11

CI becomes larger

Question 12

Is the sample size increase, our CI becomes wider of narrower?

Answer 12

Narrower (more precise).

Question 13

Can F be negative?

Answer 13

No.

Question 14

What are the 3 measures of central tendency?

Answer 14

Mean, median, mode

Question 15

What’s the problem with the mean?

Answer 15

Very vulnerable to extreme values (outliers).

Question 16

What’s good with the median

Answer 16

Less affected by extreme scores.

Question 17

What’s the mode and its positive aspects?

Answer 17

Mode = The value that occurs most frequently.
Pros: not affected by extreme values

Question 18

Categorical variables (2)

Answer 18

Nominal (objects, unordered), Ordinal (degree, age)

Question 19

Continuous variables (2)

Answer 19

Interval (T°), Ratio (time, years…)

Question 20

Family of tests (definition)

Answer 20

Set of related hypotheses.

Question 21

Familywise Type I error rate (definition)

Answer 21

Probability of making at least one Type I error in the family of tests if the null hypotheses are true.

Question 22

Formula for Familywise Type I error rate

Answer 22

= 1 - (1- alpha)**number of family test

Question 23

Type 1 error definition

Answer 23

Reject the null when it’s true.