Question

What is your final task after finding a significant result? Why is effect size useful at this stage?

Answer 1

Answer.

In quantitative research, a statistically significant result indicates that the smaple mean is close to the population mean and that this overlap cannot be explained by chance factors alone. If we come across a result of statistical significance, then the task that remains is to see whether the difference is stable across situations or will it vary due to confounding variables such as motivation, age, size of the sample. Statistical difference in large sample study is usually a safeguard against such conflation in results. Nonetheless, if the researcher is unassured by the use of a test of statistical significance as reflecting the condition in the population, the s/he can take the advantage of a procedure such as calculating the effect size.

Effect size is an approach of quantifying the difference between two groups that has the advantage of focusing on the actual size of the difference between the two groups rather than confounding with within differences alone which is more likely to happen over the use of tests of statistical significance alone.