QUANTITATIVE RESEARCH METHODOLOGY

Correlational Research

Correlational Research

sometimes called "associational research"

sometimes referred to as a form of descriptive research because it describes existing relationships between variable.

illustrated graphically using scatterplot

What is a correlational research?

investigates the possibility of relationships between variables

there is no manipulation of variables

describes the degree to which two or more quantitative variables are related and it does so by using a correlation coefficient

Purposes of Correlational Research

To explain

clarifies understanding of important phenomena by identifying relationships among the variables

Scatterplot showing a correlation of +1.00

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Positive correlation means that high scores on one variable tend to be associated with high scores ont he other variable. While low scores on one are associated with low scores on the other.

Scatterplot showing a correlation of -1.00

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Negative correlation means that high scores on one variable are associated with low scores on the other variable and low scores on one are associated with high scores on the other.

Scatterplot showing a 0 correlation

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Purposes of Correlational Research

To predict

if a relationship of sufficient magnitude exists between two variables, it becomes possible to predict a score on one variable if a score in the other variable is known.

Prediction Studies

Scatterplots for prediction

construct a scatterplotcalculate the regression line, which is the bais for prediction

Prediction Studies

where Y'1 = the predicted score on Y (criterion variable) for individual (i)X1= individual i's sore on X (the predictor variable) a and b = values calculated mathematically from the orginal scores; constants for any given data.

Y'1= a + bX1

Prediction equationexpress the regression line in the form of a prediction equation, which has the following form:

Other Correlational Techniques

Multiple Regression

enables researchers to determine a correlation between a criterion variable and the best combination of two or more predictor variables

The coefficient of multiple correlation is symbolized by R. It indicates the strength of correlation between the comination of the predictor variables and the criterion variables.

Other Correlational Techniques

The Coefficient of Multiple Correlation

symbolized by R (multiple regression), which indicates the strength of correlation between the combination of the predictor variables and the criterion variables

Other Correlational Techniques

The Coefficient of Determination

the square of the correlation between a predictor and a criterion variable symbolized by r2 (simple regression)

indicates the percentage of the variability among the criterion scores that can be attributed to differences in the scores on the predictor variable

Other Correlational Techniques

The Discriminant Function Analysis

Used when the criterion variable is categorical

Other Correlational Techniques

The Factor Analysis

determines whether many variables can be described by a few factors

Path Analysis

tests the likelihood of a casual connection among three or more variables

Steps in Correlational Research

Problem Selection

Sample Determination

Identification of Instrument Form

Design

Data Collection

Analysis and Interpretation