We introduce two simple new variants of the Jackknife Instrumental Variables (JIVE) estimator for overidentified linear models and show that they are superior to the existing JIVE estimator, significantly improving on its small sample bias properties. We also compare our new estimators to...

A variety of public campaigns, including the "Just Say No" campaign of the 1980s and 1990s that encouraged teenagers to "Just Say No to Drugs", are based on the premise that teenagers are very susceptible to peer influences. Despite this, very little is known about the effect of school peers on...