Pearson Product-Moment Correlation Coefficient

     Pearson Product-Moment Correlation Coefficient

Written by Ari Julianto

The term of Pearson Product-Moment Correlation Coefficient (usually symbolized r), or correlation coefficient mostly used in statistic. In educational research is used especilly to find out the correlation or relationship.

Basically, Pearson Product-Moment Correlation Coefficient (sometimes referred to as the PPMCC or PCC, or Pearson's r) is a measure of the degree of linear relationship between two variables, usually labeled X and Y. While in regression the emphasis is on predicting one variable from the other, in correlation the emphasis is on the degree to which a linear model may describe the relationship between two variables. In regression the interest is directional, one variable is predicted and the other is the predictor; in correlation the interest is non-directional, the relationship is the critical aspect.

The Pearson product-moment correlation coefficient is widely used in the sciences as a measure of the strength of linear dependence between two variables. It was developed by Karl Pearson from a related idea introduced by Francis Galton in the 1880s.

There are some requirements for PPMCC measurement, they are"
a. The sample taken by using random sampling,
b. The data that will be tested must be homogen,
c. The data that will be tested must be normal distribution,
d. The data that will be tested is linear.
e. Independent variable (x) and the dependent variable (Y) must be in interval scale or ratio.

The function of PPMCC in statistic in to test the generalization ability (significanse) of the research result. There are two kinds of PPMCC for measurement, they are"

a. For a population
Pearson's correlation coefficient when applied to a population is commonly represented by the Greek letter ρ (rho) and may be referred to as the population correlation coefficient or the population Pearson correlation coefficient.

b. For a sample
Pearson's correlation coefficient when applied to a sample is commonly represented by the letter r and may be referred to as the sample correlation coefficient or the sample Pearson correlation coefficient. We can obtain a formula for r by substituting estimates of the covariances and variances based on a sample into the formula above. 

The PPMCC value is symbolized as r (rho). The value of PPMCC is between -1 < r < 1. If r value = 0, it meanis there is not correlation or there is no relationship between independent variable and dependent variable.

If r value = +1 it means there is a positive correlation between independent variable and dependent variable. And if r value = -1 it means there is a negative correlation between independent variable and dependent variable.

How to measure the research result completely by using Pearson Product-Moment Correlation Coefficientcan be seen and downloaded (in Bahasa Indonesia) HERE.

Hope today's posting will be useful for all of us. Amien.