Treatment of weights in Records object constructor, Part 2

[martinholmer]

Pull request #844, which was merged on August 10, 2016, included the following code in the Records class constructor:

        # weights must be same size as tax record data
        if not self.WT.empty and self.dim != len(self.WT):
            frac = float(self.dim) / len(self.WT)
            self.WT = self.WT.iloc[self.index]
            self.WT = self.WT / frac

The calculation of frac has already been discussed in issue #1439.

An additional problem with the above code is that it ignores the fact that the weights vary from year to year, and therefore, applying one value of frac to weights in all the years creates unnecessary variation in sample weights across years.

@MattHJensen @feenberg @hdoupe

[martinholmer]

Issue #1440 has been resolved by the merge of pull request #1441.