Correlational StudiesCorrelational Studies

A way of establishing whether there is a A way of establishing whether there is a relationship between two variablesrelationship between two variables

Assessing the strength of that relationshipAssessing the strength of that relationship

NB: unlike experiments, correlational NB: unlike experiments, correlational studies do not tell you about causal studies do not tell you about causal relationshipsrelationships

Correlational StudiesCorrelational Studies

Measure the two variables to obtain two Measure the two variables to obtain two sets of paired scoressets of paired scores NB there is no IV or DVNB there is no IV or DV

Analyse the relationship by:Analyse the relationship by: Drawing a scatterplotDrawing a scatterplot Calculating a correlation coefficientCalculating a correlation coefficient

Types of CorrelationTypes of Correlation

PositivePositive As one variable rises, so does the otherAs one variable rises, so does the other

NegativeNegative As one variable rises, the other fallsAs one variable rises, the other falls

Correlational StudiesCorrelational Studies

Research question: is there a relationship Research question: is there a relationship between stress and illness?between stress and illness? Variable 1: Variable 1: scoresscores on a stress questionnaire on a stress questionnaire Variable 2: number of Variable 2: number of days absentdays absent from from

college since Septembercollege since September

HH11: There will be a : There will be a positivepositive correlation correlation between stress scores and number of between stress scores and number of absencesabsences

Correlational StudiesCorrelational Studies

Research question: is there a relationship Research question: is there a relationship between absence from college and final between absence from college and final AS marks?AS marks? Variable 1: absencesVariable 1: absences Variable 2: final AS mark (Max 300)Variable 2: final AS mark (Max 300)

HH11: There will be a : There will be a negativenegative correlation correlation between absences and AS marksbetween absences and AS marks

Correlation CoefficientCorrelation Coefficient

A statistical method for assessing the A statistical method for assessing the strength of a correlationstrength of a correlation

The sign (+ or -) tells you the direction of The sign (+ or -) tells you the direction of the correlationthe correlation

The number (between 0 and 1) tells you The number (between 0 and 1) tells you the strengththe strength