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A Short Guide to Determining Sample Size and Statistical Power

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S tatistical power depends on factors such as sample size, expected effect, participation, and variation in outcomes. Larger samples and stronger effects increase power, while low participation, unequal group sizes, and cluster randomization can reduce it.  The guide published by  t he Abdul Latif Jameel Poverty Action Lab (J-PAL)  provides  six ‘rules of thumb’ that affect sample size and statistical powe r. In brief ,  this guide   explains that sample size should be determined based on the expected effect, outcome variation, participation, and study design .  Consequently, cluster-based studies usually require a larger total number of participants to achieve the same level of statistical power. Link to the doc:  https://www.povertyactionlab.org/sites/default/files/research-resources/2018.03.21-Rules-of-Thumb-for-Sample-Size-and-Power.pdf Citation:  The Abdul Latif Jameel Poverty Action Lab (J-PAL), 2018.   Six rules of thumb for deter...