/* UMD ECON-626 FALL 2019 Power, PART 2: multiple periods (the case for more T) */ set more off // consider typing "help sampsi" // 2.1. // we have a guess about the mean among CONTROL = 0 // we have a guess about the mean among TREATMENT = 0.5 // we have a guess about the SD of the outcome = 1 // we want to have enough observations for power = 0.80 // what sample size is needed? use the sampsi command. // 2.2. // to these four options, add: // pre(1) post(1) r1(0) r01(0) // meaning // one pre-treatment observation per unit // one post-treatment observation per unit // zero correlation from pre to post // zero correlation among post treatment observations // nothing changes for two methods, but a change for one method. why? // 2.3. // now change the correlations (r1 and r01) which had been set to zero: // first so they are both 0.2, // then so they are both 0.4, // then so they are both 0.6. What happens? // 2.4. // now with each of those correlations, // try setting the number of "pre" observations to zero, // and the number of "post" observations to 2. // What changes? Why?