---
url: "https://questionstar.com/principles-of-survey-research/chapter-4/slide-121.html"
title: "Sampling: Two General Methods"
type: "lehrbuch-slide"
chapter: 4
chapterTitle: "Sampling"
slide: 121
---

# Sampling: Two General Methods

*The sample is drawn based on the personal judgment of the researcher — often at random (convenience sample, e.g. passersby in a shopping mall).*

Method 1

Non-probability Sampling

The sample is drawn based on the **personal judgment of the researcher** — often at random ( *convenience sample* , e.g. passersby in a shopping mall).

Usually **inexpensive** ; allows a rough estimate of the population parameters.

But: the **sampling error** cannot be calculated → results are **not representative** and cannot be generalized to the population.

Method 2

Probability Sampling

The sample is selected based on the **principle of randomness** .

Allows **statistical techniques** to determine the accuracy of the estimated population parameters as well as to assess their **confidence intervals** .

Results are **generalizable** and can be extended to the population.

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*Slide 121 of 274 · Chapter 4: Sampling · Principles of Survey Research · Dr. Paul Marx*