# Duration Correlations

## Overview

Duration correlations make it possible to relate the sampling of durations between multiple activities.

Correlations are ONLY available between activities, not between hammocks, LOE's, WBS summaries, milestones, or benchmarks.

For example, if the duration of an activity is sampled at the upper end of its range:

- You may want the duration of another activity to also be sampled at the upper end of its range (positive coefficient)
- Or you may want the duration of another activity to be sampled at the lower end of its range (negative coefficient)
- Duration correlations are defined using coefficients from -1 to 1.

#### Coefficient Behavior

Goal | Example | Coefficient |
---|---|---|

Strong | A sampled high, B sampled high | High positive, e.g. "1" |

Weak | A sampled high, B sampled somewhat high | Low positive, e.g. ".25" |

Weak inverse | A sampled high, B sampled somewhat low | Low negative, e.g. "-0.25" |

Strong inverse | A sampled high, B sampled high | High negative, e.g. "-1" |

Tip

Correlations can be defined in P6 and imported. For more info, see Mapping User Defined Fields.

#### Defining Correlations

- Click the
**Ranging**driver. - Select an activity from the upper list.
- Click the
**View**button above the bottom list and choose**Duration and Cost****.** Check the box in the

**Correlate**column next to a desired activity in the lower list.- Adjust the value in the
**Coefficient**column as necessary.

Required columns will display a **Warning** icon. If none of the required columns are visible, they must be turned on (see Customizing Columns). So long as any column contains a warning, the entire row will be colored red.

Tip

At any time, rows with warnings can be found by typing "error" or "warning" into the search box above the list.

## Mutual Exclusivity Coefficient Warning

Any coefficient between -1 and 1 is technically valid; however, a single coefficient is always taken in consideration with every other coefficient during simulation. For this reason, it is possible that a single coefficient makes the entire set incalculable. Note, however, that this value by itself is not incorrect and could be accepted if other coefficients were modified. Take the following activities and their coefficients:

Correlation between | Coefficient | Order defined |
---|---|---|

A and B | 1 | 1 |

B and C | 1 | 2 |

C and A | -1 | 3 |

In this case, it is the correlation between C and A at "-1" which causes the entire set to be both positive and negative simultaneously and hence reset; however, if the order entered were 1 then 3 then 2, it is the correlation between B and C that would be invalid. Similarly, if the other coefficients were modified first to also be negative, then no error would arise.

In addition to positives and negative coefficients, correlations may become incalculable due only to the variance between coefficients themselves.

## Copy/Paste/Fill Down

Once entered, correlations can be copied and pasted or filled down to save time. For details, see Interface Tour.

## Available Table Columns

For details on customizing columns, filtering, sorting, and organizing by WBS, see Interface Tour.

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