When planning an attack on a fire, the length and width of the line must be estimated, along with the capabilities of the hand crew(s), to determine how many crews will be needed. Generally, a 15-person crew should be able to construct a 3-foot fireline around a 1-acre grass fire in 1 hour. Below are some average ideal rates for hand crew production rates in various vegetation.

Hand crews primarily construct fireline but can also assist on hose lays, firing operations, protecting structures, mopping up, cleaning up, and other logistical support functions. It is important to match the task to crew capabilities. Use the best, most experienced crews for the toughest jobs and the hottest firelines. Crew effectiveness is controlled by these factors:

Standard deviation, or variance, is a measure of the closeness of each term to the average (mean). If the terms are all close to the mean or average, then the standard deviation will be small and the mean can be considered an accurate approximation of the distribution.

The deviation of a set of numbers is the difference between the average and the individual terms.

Example 1 - Jane paces off the following fire run lengths. Find the deviation of the fire run lengths, given as 6.5, 6.0, 8.0, and 7.5 chains.

Step 1. Calculate the average (see Section 9.3). Sum the numbers and divide by the number of individual elements: 28/4 = 7.0 

Step 2. Now, subtract each term from the average.
6.5 - 7.0 = -0.5
6.0 - 7.0 = -1
8.0 - 7.0 = 1.0 
7.5 - 7.0 = 0.5