1.3 Quantitative Research - Correlational Studies

Question 1

What is a correlation?

Answer 1

A correlation is a measure of linear relationship between two variables and graphically is a straight line that best approximates the scatter plot

Question 2

How are correlations different from experiments?

Answer 2

Different from experiments as no variable is manipulated

Question 3

How can correlations be illustrated?

Answer 3

Can be illustrated graphically through scatter plots

Question 4

What does one coordinate on a correlation graph show?

Answer 4

Coordinate of a spot gives individual person’s score

Question 5

What is a positive correlation?

Answer 5

Positive correlation - as X increases, Y - increases

E.g if a person gets a high score on one variable they’ll get a high score on the other

Question 6

What is the main rule when forming a conclusion from correlations?

Answer 6

CORRELATION DOES NOT IMPLY CAUSATION

-only know there’s a link

Question 7

What is a negative correlation?

Answer 7

when one variable increases the other variable decreases

Question 8

What is the relation between the gradient and the strength of the correlation?

Answer 8

The steeper the line the stronger the correlation

Question 9

What range is the correlation coefficient?

Answer 9

A correlation coefficient can vary from -1 to +1

Question 10

What is a perfect correlation? What correlation coefficient?

Answer 10

A perfect correlation of 1 / -1 is a straight line with the slope of 45 degrees, i.e as one variable increases by one unit, the other variable increases/decreased by exactly one unit

Question 11

What does the correlation close to 0 look like? What does it show?

Answer 11

A correlation close to 0 is a straight line

Shows that there is no relationship between the two variables i.e if a person scores highly on X this tells us nothing about their score on Y

Question 12

What are important factors when interpreting a correlation?

Answer 12

• effect size

- statistical signifigance

Question 13

What is the effect size?

Answer 13

Effect size - absolute value of the correlation coefficient

Question 14

What is statistical signifigance?

Answer 14

likelihood that a correlation of this size has been obtained by chance

I.e what is chance that if study is repeated with different sample, correlation will turn to 0

Question 15

What influences statistical signifigance?

Answer 15

sample size

Question 16

How does a small sample size affect statistical significance?

Answer 16

With small samples cannot be sure that an obtained correlation even if it is relatively large, has not been obtained due to random chance

Question 17

How can we determine the probability of a correlation being obtained by chance?

Answer 17

The probability that a correlation has been obtained due to random chance can be estimated, but there are conventional cut-off points when results are considered to be “statistically significant” or not
Convention cut-off point for statistical significance is 5%

Question 18

What types of correlations do scientists look for?

Answer 18

Scientists look for statistically significant correlations with large effect sizes

Question 19

What are 3 limitations of correlational studies?

Answer 19

• third variable problem
• curvilinear relationships
• spurious correlations

Question 20

What is a third-variable problem?

Answer 20

a third variable may correlate X and Y and explain the correlation between them

Question 21

What is a curvilinear relationship?

Answer 21

variables are sometimes linked non-linearly and if a straight line is drawn, we would obtain a small to medium correlation coefficient

Question 22

What are spurious correlations?

Answer 22

When a study involves calculating multiple correlations between multiple variables, there is a possibility that some of the statistically significant correlations would be the result of random chance

Question 23

When do spurious correlations occur?

Answer 23

If we only choose correlations that fit our hypothesis (bias)

When we calculate 100
correlations and only pick ones that turned out to be significant, increases the chance that we have picked spurious correlations
Methodological concern

Question 24

How is sampling generalisability decided in correlational studies?

Answer 24

Firstly target population is identified depending on the aims of the study and then a sample is drawn from the population using a sampling type (same as in an experiment)

Question 25

What is generalisability in correlational studies linked to?

Answer 25

Generalisability of findings in correlational research is DIRECTLY linked with sampling and depends on REPRESENTATIVENESS of sample (population validity)

Question 26

On what levels can bias in correlational research occur?

Answer 26

Can occur on the level of variable measurements (bias in observational data) and on the level of interpretation of findings

Question 27

What 3 biases are on the level of interpretation of findings?

Answer 27

• curvilinear relationships
• third variable problem
• spurious correlations

Question 28

How can curvilinear relationship (between variables) bias be reduced?

Answer 28

If suspected researchers should generate and study scatter plots

Question 28

How can a correlational study be more credible (third variable problem)?

Answer 28

research more credible if researcher considers potential third variable in advance and includes them in research in order to explicitly study links between X and Y and third variable

Question 28

How can spurious correlation bias be reduced and credibility increased?

Answer 28

To increase credibility, the results of multiple comparisons should be interpreted with caution

Effect sizes considered together with level of statistical significance