Correlational ResearchResearch Methodology – ENGL 6001

by Ihsan Ibadurrahman – G1025429

What is a correlational research?It aims to look at an empirical relationship

between two variables such that (1) changes in one are associated with changes in the other or (2) particular attributes of one variable are associated with particular attributes of the other. (Babbie, 2007)

Not to be confused with ‘association’ – Correlation has a specific technical meaning and needs statistical requirements for it, whereas association is a more general idea. (Neuman, 2011)

Why do we use a correlational research?As a first step prior to

experimentation As one of the criteria used to

determine Nomothetic Casuality.When experiments cannot be

conducted (for ethical or practical reasons)

A word of cautionCorrelational studies can suggest

that there is a relationship between two variables, but they cannot prove that one variable causes a change in another variable. In other words, correlation does not equal causation.

Out-of-class language learning

English performance in class

How to conduct a correlational research?

Variables are identifiedQuestions and/or hypotheses are

statedA sample is selectedData are collectedCorrelations are calculatedResults are reported

Step 1: Identifying Variables“Predictor” variable – the

variable(s) that are believed to predict the outcome, also called independent variable

“Criterion” variable – the variable to be predicted, the outcome, also called the dependent variable.

Step 2: Stating Questions Is level of education (independent

variable) related to family income (dependent variable)?

Do people who eat more eggs (independent variable) have higher cholesterol levels (dependent variable)?

Do students who employ out-of-class strategies (independent variable) more often have higher English scores (dependent variable)?

Step 3: SamplingRandom SamplingConvenient / Purposeful samplingA minimum of 30 samples is

required

Step 4: Gathering data Naturalistic Observation

Naturalistic observation involves observing and recording the variables of interest in the natural environment without interference or manipulation by the experimenter.

The Survey MethodIn this method, a random sample of participants completes a survey, test, or questionnaire that relates to the variables of interest.

Archival ResearchArchival research is performed by analyzing studies conducted by other researchers or by looking at historical patient records.

Step 5: Calculating correlationsTo calculate a numerical value of a

correlation we can use Pearson’s product moment correlation cooficcient or correlation coefficient with the symbol of the lowercase letter ‘r’.

A correlation coofficient ranges from -1.0 to +1.0, with -1.0 indicating a perfect linear negative correlation and +1.0 a perfect linear positive correlation.

Interpretation of the Strength of Correlations

00 - .20 – Very Weak.21 - .40 – Weak.41 - .60 – Moderate.61 - .80 – Strong.81 – 1.00 - Very Strong

Different statisticians may have similar but slightly different scales.

Different statisticians may have similar but slightly different scales.

Step 6: Reporting resultsPositive Correlations: Both variables increase

or decrease at the same time. A correlation coefficient close to +1.00 indicates a strong positive correlation.

Negative Correlations: Indicates that as the amount of one variable increases, the other decreases (and vice versa). A correlation coefficient close to -1.00 indicates a strong negative correlation.

No Correlation: Indicates no relationship between the two variables. A correlation coefficient of 0 indicates no correlation.

Correlations

Scatter plots are often used to depict correlations

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This chart shows a strong positive correlation

This chart shows a strong positive correlation

Correlations

Scatter plots are often used to depict correlations

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This chart shows a strong negative correlation

Correlations

Scatter plots are often used to depict correlations

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This chart shows virtually no correlation

This chart shows virtually no correlation

How to calculate correlations

Excel has a statistical function. It calculates Pearson Product Moment correlations.

SPSS (a statistical software program for personal computers used by graduate students) calculates correlations.