Correlation

• Correlational research is used to investigate the relationship between two or more variables.
• The correlation coefficient (r) measures the strength and direction of the linear association between two continuous variables.
• A positive correlation indicates that as one variable increases, so does the other variable.
• A negative correlation indicates that as one variable increases, the other decreases.
• Zero correlation means there is no linear association between the variables.
• Zero correlation means there is no linear association between the variables.
• Pearson's product-moment correlation coefficient (r) is commonly used when both variables are measured on an interval/ratio scale.
• Pearson's product-moment correlation coefficient (r) is commonly used when both variables are measured on an interval scale.
• Spearman's rank correlation coefficient (ρ) can be used with ordinal data.
• Kendall's tau-b correlation coefficient (τb) is another measure of concordance/discordance for ranked data.
• Spearman's rank correlation coefficient (ρ) can be used to measure the relationship between two ordinal variables or when data have been transformed into ranks.
• A positive value indicates that as one variable increases, so does the other; a negative value indicates that as one variable increases, the other decreases.