topic Re: Rank function missing few ranks in SAS Programming

Rank function missing few ranks

abhim701 — Mon, 21 Nov 2016 17:20:39 GMT

I am trying to use Rank function on a numeric variable num_var to get a new variable num_var_1 with ranks. In my output I get the new variable num_var_1 with ranks 0,2,3,4,5,6,7,8,9. Rank 1 is missing.

proc rank data = source_data out = output groups =10 ties = low;
var num_var.;
ranks num_var_1;
run;

What could be the possible reason for this?

Thanks in advance for help.

Regards

Abhishek

Re: Rank function missing few ranks

PGStats — Mon, 21 Nov 2016 17:48:25 GMT

There must be a large number of ties at the minimum value, more than 20% of your data. Ties=low will give rank 0 to those obs.

Re: Rank function missing few ranks

abhim701 — Mon, 21 Nov 2016 18:16:50 GMT

Thanks for the help! I got it now.

Re: Rank function missing few ranks

abhim701 — Mon, 21 Nov 2016 18:33:36 GMT

I tried ties = high. This also gives me the same output.

0,2,3,4,5,6,7,8,9.

I was expecting

1,2,3,4,5,6,7,8,9

any comments?

Re: Rank function missing few ranks

PGStats — Mon, 21 Nov 2016 19:21:59 GMT

Can't say without seeing the data. One way to break the ties is to add a small random component to the data:

data source_data_rnd;
set source_data;
num_var_rnd = num_var + rand("UNIFORM")*0.00001;
run;

proc rank data = source_data_rnd out=output(drop=num_var_rnd) groups=10;
var num_var_rnd;
ranks num_var_1;
run;

Re: Rank function missing few ranks

Ksharp — Tue, 22 Nov 2016 02:37:14 GMT

Try
 ties = dense

Re: Rank function missing few ranks

Rick_SAS — Tue, 22 Nov 2016 15:31:45 GMT

For a discussion of some common reasons this could happen, see the article "Binning data by quantiles."