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Convenience & Self-Selected Samples

Convenience & Self-Selected Samples

Author: Sophia Tutorial
Description:

Determine convenience and self-selected samples.

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Tutorial
what's covered
This lesson will explain two types of samples: convenience and self-selected samples. Our discussion breaks down as follows:

  1. Representative Samples
  2. Non-Representative Samples
    1. Convenience Samples
    2. Self-selected Samples


1. Representative Samples

One of the things that we know about sampling is that it's important for samples to be representative of the population, also known as a representative sample. What we mean by that is when we take our sample--which is a subset of a larger population--we want this sample to behave just like the population would if we sampled them all.

did you know
Now, sampling everybody is not a sample at all; that’s called a census.

We want the sample to behave as similar to the population as possible so that when we calculate statistics from our data, the statistics are as accurate about the population as they can be.

big idea
The sample should represent the group/population at large, so it’s important individuals are selected carefully for the sample. That way, accurate information will be gained and can be used to describe the group/population at large.

The goal is to generalize what is found in the sample and apply it to the people outside of the box, or the population.

term to know

Representative Sample
A sample that accurately reflects the population.

2. Non-Representative Samples

The two methods analyzed in this tutorial have major flaws--these two designs do not result in representative samples. They are conducted often, so it’s important for you to recognize them.

2a. Convenience Samples
A convenience sample that is easily obtained is not valid because people in similar locations often feel the same way.

IN CONTEXT

Suppose there is a crowd of people at a mall and there is one guy with a clipboard, and he wants some data. He might take the people nearest to him, and say, “Hey, would you like to take my survey, please?”

The people he asks might be representative of the population, but they might not. They all simply happen to be at the same place at the same time. This means they might have some similarities that could make them not representative of the larger population. The risk of them not representing the group/population at large is too high.

EXAMPLE

If you ask people about their spending habits, and they all happen to be shopping in the headphones section, that probably means they have similar ideas about how they should spend their money.

term to know

Convenience Sample
A sample that is easily obtained. It is often not representative of the population.

2b. Self-selected Samples
Next, let's discuss self-selected samples, which are also called voluntary response samples. These are samples where people can choose to participate.

EXAMPLE

Focus groups are a common example of self-selected samples.

Participants who feel very strongly about the subject at hand are likely to be the volunteer for the self-selected sample. On the other end of the spectrum, participants may be compensated for their time and may simply tell the interviewer what they want to hear.

EXAMPLE

If your focus group is about politics, you might get only the very, very liberal people or the very, very conservative people. You might get the most extreme viewpoints but none of the viewpoints in the middle. Or, there are also a lot of people who are ambivalent about politics. They don't really care, but they want to get paid if this is a sample that offers compensation or another type of reward like free lunch.

term to know
Self-Selected (Voluntary Response) Sample
A sample that the participants choose to be a part of.


summary
Representative samples are important if we want to accurately generalize our findings to the population. Convenience samples render people who are simply in the vicinity and happen to be at the same place at the same time. Self-selected samples are also called “voluntary response” and tend to elicit either strong opinions or no opinion at all.

Good luck!

Terms to Know
Convenience Sample

A sample that is easily obtained. It is often not representative of the population.

Representative Sample

A sample that accurately reflects the population.

Self-Selected (Voluntary Response) Sample

A sample that the participants choose to be a part of.