SOLUTION: Sandy is desperate to complete her study. Instead of planning out who she wants to take her survey, she stops her classmates after class and hands out the survey to anyone willi

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Question 1198179: Sandy is desperate to complete her study. Instead of planning out who she wants to take her survey, she stops her classmates after class and hands out the survey to anyone willing to stay. What type of sampling is this described as?
A) accidental sampling
B) stratified sampling
C) simple random sampling
D) systematic sampling
Answer by math_tutor2020(3816) About Me  (Show Source):
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Answer: A) accidental sampling


Explanation:

Accidental sampling, aka convenience sampling, is when you select those closest to you or those easiest to access.
As you can probably guess, this form of sampling is heavily biased.
It should be avoided at all times.

Stratified sampling is when you split a population into subgroups that don't overlap. Then you sample members from each subgroup.
A classic example would be men vs women.
Be sure your sample has the same proportion compared to the population.
For example, if the ratio of women to men is 3:1, then be sure your sample has 3 times as many women compared to men.

A similar idea is cluster sampling, which students often mix up with stratified sampling. The ideas are similar but not the same. Cluster sampling is when you assign people to different non-overlapping subgroups, then randomly select some subset of groups, in which ALL people are surveyed in those groups.
Example: Randomly select 3 buildings from a large city, and then survey everyone in those selected buildings. Cluster sampling can get very expensive if your clusters are too large.

Simple random sampling (SRS) is when a random number is generated, or a name is pulled randomly out of a hat.
Computer software is generally used here to make the process as random as possible.
Though computers are known to use pseudo-random processes, and it might be better to use something like weather patterns to help generate purely random values.

If your sampling technique is something like "I'll select every 10th person", then you are conducting systematic sampling. There's a set pattern or rule to follow.