diff --git a/education/statistics/Sampling.md b/education/statistics/Sampling.md
index 371b3d2..561ca57 100644
--- a/education/statistics/Sampling.md
+++ b/education/statistics/Sampling.md
@@ -36,4 +36,6 @@ 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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+The expected value for a sample percentage equals the population percentage. The standard error for that percentage = `(SE_sum/sample_size) * 100%`
+
+To determine by how much the standard error is affected, if `n` is the sample size, the standard error changes by $\frac{1}{\sqrt{n}}$
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