Sample Size
Assume a sample size of 52 was calculated
Allocation of samples
1. Equal
high flow - 26
low flow - 26
2. Proportional
a. based on time
high flow (.252)(52) = 13.1 => 13
low flow (.748)(52) = 38.9 => 39
b. based on water load
high flow (.70)(52) = 36.4 => 36
low flow (.30)(52) = 15.6 => 16
3. Optimal (using strata based on water load and assuming the high flow period is twice
as variable as the low flow period)
high flow
43
low flow
9
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