Statistical Tests (- sign)

Question 1

When is Spearman’s rho used?

Answer 1

When a relationship (correlation) is predicted between two sets of data, the data is at least ordinal and the data are pairs of scores from a repeated measures or match pairs design

Question 2

Why would data come in pairs (Spearman’s)?

Answer 2

Either because the same participant took part in both conditions (repeated measures) or because the participants are matched up (matched pairs)

Question 3

What is Spearman’s rho also used to create?

Answer 3

Correlational coefficients which tells the researcher about the strength and direction of a correlation

Question 4

What are all Spearman’s rho scores between and what do the scores mean?

Answer 4

All between -1 and 1
If Spearman’s rho is negative that means a negative correlation, if its positive it means a positive correlation
The closer to -1 and 1 the Spearman’s rho is, the stronger the correlation

Question 5

How does a Spearman’s rho test work?

Answer 5

The test gives an observed value (called rs)
Once you’ve got rs, look at the critical values table to see if the results are significant
You need to know the sample size (N) for this

Question 6

What is Pearson’s r test?

Answer 6

A parametric test used when a relationship (correlation) is predicted between two sets of data, the data is normally distributed, the data is interval/radio data and the data are in pairs of scores from repeated measures or matched pairs design

Question 7

When would Pearson’s r test be used?

Answer 7

When data comes in pairs (repeated measures or matched pairs)
Data is interval//ratio level

Question 8

What are Pearson’s r test also used to create?

Answer 8

Correlational coefficients which tells the researcher about the strength and direction of a correlation

Question 9

What are Pearson’s r scores always between and what do they mean?

Answer 9

All between -1 and 1
If Spearman’s rho is negative that means a negative correlation, if its positive it means a positive correlation
The closer to -1 and 1 the Spearman’s rho is, the stronger the correlation

Question 10

How does the Pearson’s r test work and what do you need to know?

Answer 10

The test gives you an observed value (called r)
Once you’ve got r, look at the critical values table to see if the result is significant
You need to know the degree of freedom for looking at the table which is calculated N(sample) - 2

Question 11

In both Spearman’s rho and Pearson’s r what must the calculated value of either rs or r be in order for significance to be shown?

Answer 11

Equal to or greater than the critical value in the table

Question 12

What is the Wilcoxon test?

Answer 12

Also known as the Wilcoxon signed-matched ranks. It is used when a difference is predicted to occur between two sets of data, the data is normally distributed, the data is of at least ordinal level and a related measure has been used

Question 13

When do psychologists use the Wilcoxon test?

Answer 13

The data come in pairs (repeated measures or matched pairs)

The data from two different conditions can be put in order of size

Question 14

How does the Wilcoxon test work and what do you need to know?

Answer 14

Gives you an observed value, called T
Once you have T, look at the critical values table to see if the results are significant
Need to know the sample size (N - for the Wilcoxon test), you only use pairs of scores that are different

Question 15

What must the value of T be in the Wilcoxon test to shown significance?

Answer 15

Equal or less than the critical value - if it is, the result is significant and the null hypothesis can be rejected

Question 16

What is the Mann-Whitney test?

Answer 16

Used when a difference is predicted between two sets of data, the data is of at least ordinal level and an independent group design has been used

Question 17

When would psychologists use a Mann-Whitney test?

Answer 17

There is only one result for each participant - no participant appears in the results for both groups (independent group)
Data from the two different conditions can be put into order of size

Question 18

How does the Mann-Whitney test work?

Answer 18

Gives two observed values called U1 and U2- (one for each of samples)
Once you have both U values, the lowest one becomes the U value and is used to see if the results are significant

Question 19

Why are their two tables in the Mann-Whitney test?

Answer 19

One for one-tailed hypothesises and one for two-tailed hypothesises
First table= critical values of U for the one tailed Mann-Whitney test at p=0.05 or the two-tailed at p=0.10
Second table = critical values of U for the two/one?-tailed test at p=0.25 or the two tailed at p= 0.05

Question 20

How is significance decided in the Mann-Whitney test?

Answer 20

If U is equal to or less than the critical value, the result is significant and the null hypothesis can be rejected

Question 21

What is the related t-test?

Answer 21

Also called the dependent t-test
parametric test that is used when a difference is predicted between two sets of interval/ratio data and the data is gathered using repeated measures or matched pairs

Question 22

When do psychologists use the related t-test?

Answer 22

The data comes from research that uses the repeated measures or matched pairs design
The data is normally distributed and is interval data

Question 23

How does the related t-test work and what do you need to know

Answer 23

It gives you an observed value called t
Once you have t, look at the critical values tables to see if the results are significant
For this, need to work out the degrees of freedom to help find the critical value

Question 24

How do you work out the degrees of freedom (Df) (related t-test)?

Answer 24

N (number in sample) - 1

Question 25

How is significance determined in the related t-test?

Answer 25

Calculated value of t must be equal to or greater than the critical value for significance to be shown

Question 26

What is the unrelated t-test?

Answer 26

Also called the independent t-test
A parametric test that is used when a difference is predicted between two sets of interval/radio data and the data is gathered using independent groups design.

Question 27

How does the unrelated t-test work and what will you need?

Answer 27

The test gives an observed value called t
Once you have t, look at the critical values table to see if the results are significant
Need to work out the degrees of freedom to help find the critical value

Question 28

How do you work out degrees of freedom for the unrelated t-test?

Answer 28

Nx (number of RPS in the 1st sample) + Ny(Number of RPS in the 2nd sample) - 2

Question 29

In the unrelated t-test, what happens if the t is a negative number?

Answer 29

The negative sign is ignored

Question 30

How is significance determined in the unrelated t-test?

Answer 30

Calculated value of t must be equal to or greater than the critical value for significance to be shown

Question 31

What is the chi-squared test?

Answer 31

Used when a difference is predicted between two sets of data. The data is at least nominal and an independent group design has been used. It’s possible to use chi-squared with correlations as a test of association

Question 32

When do psychologists use the chi-squared test?

Answer 32

The data is about frequencies for different categories (this is nominal data and it is best if these categories don’t have a particular order like size)
The data is from Independent group design, meaning each RPS only appears once in the results

Question 33

How does the Chi-squared test work and what will you need to know?

Answer 33

Gives an observed value called X2
Once you’ve got this, look at the critical values table to see if the results are significant
Will need to know what the degrees of freedom are

Question 34

In the chi-squared test how are the degrees of freedom worked out?

Answer 34

(Number of rows -1) x (Number of columns -1)

Question 35

How is significance determined in the Chi-squared test?

Answer 35

Calculated value of X2 must be equal to or greater than the critical value for significance to be shown