Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comment: The Essential Role of Pair Matching in Cluster-Randomized
  Experiments, with Application to the Mexican Universal Health Insurance
  Evaluation   Comment on ``The Essential Role of Pair Matching in Cluster-Randomized
Experiments, with Application to the Mexican Universal Health Insurance
Evaluation'' [arXiv:0910.3752]

28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math