Meaning of CorrelationExamples of correlation (i) Rain: Agricultural product = Relation (ii) Supply: Price = Relation (iii) Age: Playing Habit = Relation (iv) Temperature: Sale of ice cream = Relation (v) Temperature: Sale of Mobile = Relation (vi) Weight: Height = RelationCorrelation and Cause-effect relationship1. One variable may act upon the other2. The two variables may act upon each other3. The two variables may be acted upon by outside influences4. A high correlation coefficient may be derived due to sheer coincidenceDegree of CorrelationKarl Pearson's Coefficient of correlationMeaning of Karl Pearson's Coefficient of correlationKarl Pearson's Coefficient of correlation by Calculation of correlation by Direct MethodKarl Pearson's Coefficient of correlation by Calculation of correlation by Shortcut MethodKarl Pearson's Coefficient of correlation In discrete and continuous series Or Correlation in Bivariate frequency distribution Or Correlation in grouped seriesSome Important Questions for PracticeSpearman's Rank Difference MethodMeaning of Spearman's Rank Difference MethodSpearman's Ranking methodProblem of Similar marksProbable ErrorMeaning of Probable ErrorSome Important practical problems for PracticeMeaning of Correlation:The term correlation indicates the relationship in between two such variables in which with change in the value of one variable, the values of the other variable also changes. It is likely that such relationship may be obtained in two series relating to the height and weight of a group of a person. This analysis is a statistical procedure by which we can determine the degree of association or relationship between two or more variables.