---
url: "https://questionstar.com/principles-of-survey-research/chapter-4/slide-140.html"
title: "Margin of error approach: two formulas"
type: "lehrbuch-slide"
chapter: 4
chapterTitle: "Sampling"
slide: 140
---

# Margin of error approach: two formulas

*Calculating the margin of error*

![x = x̂ ± E](/principles-of-survey-research/media/formel_top.png)

x = true value of the parameter x̂ = sample value E = margin of error

For metric data

Means

Assessing means computed from the sample

![E = z · σ / √n](/principles-of-survey-research/media/formel_mittelwerte.png)

z z-value for the specified confidence level

σ Standard deviation of the parameter in the population

n Sample size

For proportions

Proportions

Assessing computed proportions

![E = z · √(π(1−π)/n)](/principles-of-survey-research/media/formel_verhaeltnisse.png)

z z-value for the specified confidence level

π Estimated value for the proportion in the population

n Sample size

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*Slide 140 of 274 · Chapter 4: Sampling · Principles of Survey Research · Dr. Paul Marx*