By default,
each observation is counted only once in the calculation
of the chart statistics. To calculate weighted statistics in which an observation
can be counted more than once, use the FREQ= option. This option identifies
a variable whose values are used as a multiplier for the observation in the
calculation of the statistic. If the value of the FREQ= variable is missing,
0, or negative, the observation is excluded from the calculation.
If you use the SUMVAR= option, then for each observation, the value
of the SUMVAR= variable is multiplied by the value of the FREQ= variable in
calculating the chart statistic.
For example, to use a variable called COUNT to produce weighted statistics,
assign FREQ=COUNT. If you also assign the variable HEIGHT to the SUMVAR= option,
then the following table shows how the values of COUNT and HEIGHT would affect
the statistic calculation:
|
Value of COUNT |
Value of HEIGHT |
Number of times the observation is used |
Value used for HEIGHT |
|
1 |
55 |
1 |
55 |
|
5 |
65 |
5 |
325 |
|
. |
63 |
0 |
- |
|
-3 |
60 |
0 |
- |
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