diff --git a/education/statistics/Sampling.md b/education/statistics/Sampling.md
index c22e7c9..371b3d2 100644
--- a/education/statistics/Sampling.md
+++ b/education/statistics/Sampling.md
@@ -36,3 +36,4 @@ An ideal sample will represent the whole population.
 | Measurement | Interviewing method influences the response, uses loaded words or ambiguities. |
 (Ch 20, stat 1040)
 
+The expected value for a sample percentage equals the population percentage. The standard error for that percentage = `(SE_sum/sample_size) * 100%`
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