If you know the formula for a statistic, you can use the Calculator to calculate it. For example, you can use the Calculator to calculate the weighted mean and the weighted standard deviation for a column of numbers.

- Choose .
- In the name cell for C1, type
`Data`. - Copy and paste, or type the following data into C1.
49.01 2.20 16.70 93.97 6.16 27.75 - In the column name cell for C2, type
`Weights`. - Copy and paste, or type the following data into C2.
5 12 8 14 9 4 - Choose .
- In Store result in variable, type
`Weighted Mean`. - In Expression, copy and paste, or enter
`SUM(C1*C2)/SUM(C2)` - Click OK.

The weighted mean is 36.2898.

C1 | C2 | C3 |
---|---|---|

Data | Weights | Weighted Mean |

49.01 | 5 | 36.2898 |

2.20 | 12 | |

16.70 | 8 | |

... | ... |

You must calculate the weighted mean before you calculate the weighted standard deviation.

The square of the weighted standard deviation is the weighted variance.

- Choose .
- In Store result in variable, enter
`Weighted SD`. - In Expression, copy and paste, or enter
`SQRT(SUM(C2*(C1-C3)^2 )/((SUM(C2/C2)-1)*SUM(C2)/SUM(C2/C2)))`###### Note

If the Weights column contains a 0, you will get an error because you can't divide by 0.

- Click OK.

The weighted standard deviation is 41.0060.

C1 | C2 | C3 | C4 |
---|---|---|---|

Data | Weights | Weighted Mean | Weighted SD |

49.01 | 5 | 36.2898 | 41.0060 |

2.20 | 12 | ||

16.70 | 8 | ||

... | ... |