## **Table 2: Survey Evidence on Randomization Methods Used by Leading Researchers**

||% WH<br>Unweighted|O HAVE EV<br>Weighted|ER USED<br>5+ experiment<br>Group|% Using Method in<br>Most Recent<br>Experiment|
|---|---|---|---|---|
|Single Random Assignment to Treatment (possibly with stratification)|80|84|92|39.1|
|Subjectively deciding whether to redraw|32|52|46|4.3|
|Using a statistical rule to decide whether to redraw|12|15|15|0.0|
|Carrying out many random assignments, and choosing best balance|24|45|38|17.4|
|Explicitly matching pairs of observations on baseline characteristics|56|52|54|39.1|
|Number of Researchers|25|25|13|23|

Notes: Methods described in more detail in the paper. Weighted results weight by the number of experiments the researcher has participated in 5+ experiment group refers to researchers who have carried out 5 or more randomized experiments

# **Table 3: How do the different methods compare in terms of Baseline Balance?**

_Simulation Results for 100 Observation Sample Size_

||Single<br>Random<br>Draw|Stratified<br>on 2<br>variables|Stratified<br>on 4<br>variables|Pairwise<br>Greedy<br>Matching|Big<br>Stick<br>Rule|Draw with<br>minmax t-stat<br>out of 1000 draws|
|---|---|---|---|---|---|---|
|**Panel A: Average difference in BAS**<br>|**ELINE betw**|**een treatme**|**nt and contr**|**ol means (in**|**std. dev.)**||
|Microenterprise profits (Sri Lanka)|0.001|0.000|-0.001|0.000|0.001|0.000|
|Household expenditure (Indonesia)|-0.002|0.001|-0.001|0.000|-0.001|-0.002|
|Labor income (Mexico)|0.000|0.000|0.000|0.000|-0.001|0.000|
|Height z-score (Pakistan)|0.001|0.001|0.000|0.000|-0.001|0.000|
|Math test score (Pakistan)|0.003|0.000|-0.001|0.000|0.002|0.000|
|Baseline unobservables (Sri Lanka)|0.000|0.000|0.000|0.000|0.000|0.001|
|Baseline unobservables (Mexico)|0.000|0.000|0.000|0.000|0.000|0.000|
|**Panel B: 95th percentile of differen**<br>|**ce in BASEL**<br>|**INE between**<br>|**treatment**<br>|**and control**<br>|**means (in**<br>|**std. dev.)**<br>|
|Microenterprise profits (Sri Lanka)|0.386|0.195|0.241|0.312|0.324|0.091|
|Household expenditure (Indonesia)|0.390|0.145|0.191|0.266|0.328|0.107|
|Labor income (Mexico)|0.384|0.280|0.304|0.099|0.332|0.088|
|Height z-score (Pakistan)|0.395|0.160|0.206|0.119|0.319|0.089|
|Math test score (Pakistan)|0.392|0.164|0.237|0.074|0.328|0.106|
|Baseline unobservables (Sri Lanka)|0.434|0.417|0.414|0.434|0.434|0.434|
|Baseline unobservables (Mexico)|0.457|0.448|0.439|0.457|0.457|0.457|
|**Panel C: Proportion of p-values <0.**<br>|**1 for testing**<br>|**difference i**<br>|**n BASELINE**<br>|**means**<br>|||
|Microenterprise profits (Sri Lanka)|0.097|0.000|0.005|0.036|0.045|0.000|
|Household expenditure (Indonesia)|0.102|0.000|0.000|0.011|0.049|0.000|
|Labor income (Mexico)|0.100|0.015|0.029|0.000|0.053|0.000|
|Height z-score (Pakistan)|0.100|0.000|0.001|0.000|0.038|0.000|
|Math test score (Pakistan)|0.100|0.000|0.006|0.000|0.048|0.000|
|Baseline unobservables (Sri Lanka)|0.101|0.096|0.095|0.084|0.098|0.091|
|Baseline unobservables(Mexico)<br>Notes:|0.108|0.095|0.093|0.103|0.102|0.110|

Statistics are based on 10,000 simulations of each method. Details on methods and variables are in Table A2.