The panel study involved a random sample of 895 households from over 50 000 enrolled in a cash-for-work programme between September and December 2007 and 921 similar control households.
我们从2007年9月和12月登记在现金薪酬项目的50,000多个家庭中抽取了895个家庭作为随机样本，还选择了921个类似的对照家庭，然后对它们开展了小组研究。
Methods A random, double blind, and placebo control study was conducted.
方法采用随机双盲、安慰剂平行对照研究。
DESIGN: Non random and self control experimental study.
设计：非随机自身对照实验性研究。
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