Use the Weight command to give cases different weights for statistical analysis. Typically, the Weight variable brings about simulated case replication. For example, if a case has a weight of 5, it would be as if the case occurred five times in the data even though the case is physically a single record. You can use Weight to weight a sample up to a population, or you might use Weight to enter cell counts for an example table in a publication. If there is no explicit Weight variable, then the weight for each case is 1.
When SPSS Statistics reports the number of cases, it reports the weighted number of cases. With no explicit weight variable, the case weights are all 1 and the sum of the 1s equals the number of active rows. With an explicit Weight variable, the sum of the weights is the effective sample size, and in general is not equal to the number of rows.
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