Groups of population can be compared using box and whisker plots. Overall visible spread and difference between median is used to draw conclusion that there tends to be a difference between two groups or not.

__Case 2: Formula__

__Case 2: Formula__

P=DBMOVS×100P=DBMOVS×100

Where −

· PP = percentage difference

· DBMDBM = Difference Between Medians.

· OVSOVS = Overall Visible Spread.

__Rules__

__Rules__

· For a sample size of 30 if this percentage is greater than 33% there tends to be a difference between two groups.

· For a sample size of 100 if this percentage is greater than 20% there tends to be a difference between two groups.

· For a sample size of 1000 if this percentage is greater than 10% there tends to be a difference between two groups.

__Example__

__Example__

**Problem Statement:**

Describe the difference between following sets of data.

Sr. No. | Name | Set A | Set B |

1 | Max | 12 | 15 |

2 | UQ | 10 | 13 |

3 | Median | 7 | 10 |

4 | LQ | 6 | 9 |

5 | Min | 5 | 6 |

**Solution:**

Consider the following diagram:

OVS=13−6 =7 DBM=10−3 =4OVS=13−6 =7 DBM=10−3 =4

Apply the formula

P=DBMOVS×100 =47×100 =57.14P=DBMOVS×100 =47×100 =57.14

As percentage is over 33% thus there is difference between Set A and Set B. It is likely that Set B is greater than Set A.