MAKING IT USEABLE    Weighting       Use Weighted Data Except

The only times when the use of unweighted data may be appropriate is in an analysis of the sample used in NPTS for purposes of commenting on the properties of the survey sample. IN ALL OTHER USES OF THE DATA, ONLY WEIGHTED DATA SHOULD BE USED. The typical reason a data user would want to examine the sample is to determine if the cell size is sufficient for a specific analysis.

For example, from the following table, the large number of samples for trips by women using an auto (139,742) suggest that the weighted estimate would provide a good reflection of actual travel. On the other hand, the sample size for trips by men using Amtrak (16) suggests any estimate would be an inexact reflection of actual usage.

Table 3
Travel Day Person Trips (Sample Size)

Mode of Transportation

Male

Female

All

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