correlations

the ONLY terms we can use for correlations

relationship, correlation, no cause and effect, covariables, positive, negative

what is a correlational study?

used to analyse the relationship between two continuous variables (covariables)

what are covariables?

the two variables being measured by the researcher within correlational research which may or may not vary with each other

what hypothesis is this an example of: There will be a significant positive relationship between the units of alcohol consumed in a day and scores on a memory test (out of 8) 

alternative directional

what hypothesis is this an example of: There will be a significant relationship between the units of alcohol consumed in a day and scores on a memory test (out of 8

alternative non-drectional

evaluation: 2 STRENGTHS of correlations

• can be used to inspire future experimental research- bc researchers can establish both direction and strength of relationship between co-variables

• can be used when experiments are inappropriate- more ethical for the researcher to measure co-variables rather than manipulate them

evaluation: 2 WEAKNESSES of correlations

• don’t show cause and effect- cant conclude that an increase in one co-variable is caused by another co-variable or vice versa. we can only conclude that a relationship exists.

• only show that there is a relationship, not how or why covariables are related- may be other external variables that explain the relationship

What is a scatter diagram

a diagram that represents a relationship/correlation between two or more co-variables

how is data displayed in a scatter diagram

the horizontal axis represents 1 covariable and the vertical axis represents the other covariable. the data is displayed as dots on the graph. the position of each dot represents numerical data for each covariable

4 things we need on a scatter graph

title, label + scale of X and Y axis fully operationalised, accurately plot each point from table of results

how to write a title for a scatter graph

scatter diagram to show the relationship between covariable 1 and covariable 2

‘outline one conclusion from the scatter diagram in this study’ what three possible conclusions can we comment on?

• direction of relationship (positive, negative, zero)

• strength of relationship (weak, strong)

• identifying outliers if there are any

what is the scale for correlation coefficients

-1 to 1

how to identify a STRONG correlation

all data is close to the line of best fit

how to identify a WEAK correlation

data is spread out, not all close to the line of best fit

what should researchers do about outliers

leave them or it would be researcher bias

what is spearmans rho?

an inferential statistical test. the only test that can analyse if there is a relationship (e.g. experiments only see if theres a difference). used for a researcher to state whether the findings are significant or not.

what is an observed/calculated value

correlation coefficient. comes from doing a spearmans rho. falls between -1 and 1.

what is the critical value?

the value that is compared to the observed/calculated value. to be significant, the observed value must be GREATER than the critical value.

if the critical value is significant, which hypothesis do you accept?

alternative hypothesis

if the critical value is not significant, which hypothesis do you accept?

null