# How to Calculate Interquartile Range (IQR) and Semi-interquartile Range or Quartile Deviation

Interquartile Range
Interquartile range (IQR) is a measure of spread, based on quartiles, that still maintains the idea of range, but is not influenced by

# Karl Pearson’s Coefficient Method (Correlation)

Karl Pearson’s Coefficient Method
Karl Pearson’s method of coefficient of correlation is also known as Pearsonian coefficient or correlation or product correlation method.
Let X

# Scatter Diagram Method (Correlation)

Scatter Diagram Method
Scatter Diagram Method is the simplest method of studying the correlation between two variables. In this method the values of one of

# Correlation – Definition, Types, Methods of Measurements

Correlation
Correlation is a statistical tool used to study the relationship between two or more variables. Two variables are said to be correlated if the

# Mean Deviation The Absolute Measure of Dispersion

Mean Deviation Definition
Mean deviation is defined as the mean of absolute deviations of the values from the central value.
For individual series:
\[MD\left( \overline{X}

# Quartile Deviation the Absolute Measure of Dispersion

Definition of Quartile Deviation
Quartile Deviation divides the total frequency in to four equal parts. The lower quartiles Q1 refers to the values of variates