Home > Publications . Search All . Browse All . Country . Browse PSC Pubs . PSC Report Series

PSC In The News

RSS Feed icon

Mitchell finds children who lose fathers suffer at cellular level

Seefeldt says hard work alone won't allow poor to reach middle-class status in America

Shaefer says proposed plan to cover tax cuts would hurt a lot of struggling Americans

More News

Highlights

Neal Krause wins GSA's Robert Kleemeier Award

MiCDA Research Fellowship - applications due July 21, 2017

U-M awarded $58 million to develop ideas for preventing and treating health problems

Bailey, Eisenberg , and Fomby promoted at PSC

More Highlights

Ben Hansen photo

Covariate balance in simple, stratified and clustered comparative studies

Publication Abstract

Hansen, Ben, and J. Bowers. 2008. "Covariate balance in simple, stratified and clustered comparative studies." Statistical Science, 23(2): 219-236.

In randomized experiments, treatment and control groups should be roughly the same-balanced-in their distributions of pretreatment variables. But how nearly so? Can descriptive comparisons meaningfully be paired with significance tests? If so, should there be several such tests, one for each pretreatment variable, or should there be a single, omnibus test? Could such a test be engineered to give easily computed p-values that are reliable in samples of moderate size, or would simulation be needed for reliable calibration? What new concerns are introduced by random assignment of clusters? Which tests of balance would be optimal? To address these questions, Fisher's randomization inference is applied to the question of balance. Its application suggests the reversal of published conclusions about two studies, one clinical and the other a field experiment in political participation.

DOI:10.1214/08-sts254 (Full Text)

Browse | Search : All Pubs | Next