I've been following some of the apportionment threads, and wanted to pose a 
related question:  Is there an optimal legislature size from the standpoint of 
apportionment?

Let's say that you decide to apportion seats among constituencies.  We'll leave 
aside the issue of whether those constituencies will elect their 
representatives from districts within the constituencies or proportionally in 
an at-large election or whatever.  We'll just stipulate that each constituency 
gets at least one seat, and that the number they get is roughly linear in their 
population.

The common way to do this is you start off with each constituency having 1 
seat, and then you hand out the remaining seats one-at-a-time based on some 
formula.  Different people have proposed different formulas, either based on 
who is most under-represented at the moment, or who would be least 
over-represented with an extra seat, or whatever, but regardless of what 
formula you use, let's just agree that the method goes one-at-a-time.

The first few seats will mostly go to the largest constituencies.  So, if you 
have 50 states with a broad distribution of populations, and you have a 
legislative chamber with 60 seats, most of your states will be 
under-represented.  If you expand to 1000 seats or whatever, your biggest 
disproportionality problem will probably be at the low end of the scale, i.e. 
adding or removing 1 seat from a state with 5 representatives changes the ratio 
of reps to population by 20%, while adding or removing 1 seat from a state with 
100 reps changes the ratio of reps to population by 1%.

If your only concern is numerical fairness, of course, you should just keep 
adding more seats, until you reach something like the square root of the 
population.  But if you want to keep your legislature size low for practical 
reasons (i.e. in the 3 digit range), is there any good quantitative criterion 
for minimum size?

My intuition tells me that either there is no fundamental criterion here, but a 
practical one is to keep adding until most of the changes are in the median 
state.  Or keep adding until the ratio of population to reps for the median 
state equals the ratio of population to reps for the largest state, plus or 
minus some small tolerance that you decide on.

Anybody have ideas for formalizing this issue?



Alex Small
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