Correlation analysis is an important quantitative technique that is essential for Ph.D thesis and Master's dissertation. It is mainly used to determine the intensity of the association among two continuous variables that are numerically measured e.g. weight and height. Specifically, this analysis is used in statistic when a researcher wants to determine the relationship between the variables. Often it is wrongly understood that it assess the cause and effect which is not possible since the other variables not available in the research could influence the outcome. If a correlation exists among the variables then it means systematic change occurred in one variable also occurs in another variable. The variables get modified for some time. If the identified correlation is reliable on the evaluated numerical values then it can be negative or positive.
If both the variable increases simultaneously then a positive correlation is found. I.e. the greater numerical values of one variable associate with the other variable greater numerical values.
If the one variable reduces when other variable increases then the negative correlation is found. I.e. the greater numerical value of one variable associate with the other variable low numerical value.