Question

question #18
a simple random sample of 25 subjects from a population is one in which:
o a simple way was found to choose 25 subjects at random from the population.
o most, but not all, groups of size 25 have the same chance of being selected.
o any group of 25 subjects has the same chance of being the selected sample.
o we record the data provided by the first 25 subjects who respond to the survey.

question #19
mike owns a landscaping business with 72 clients. mike wants to interview a sample of clients in order to improve client satisfaction.
if he wants to avoid bias, which of the following recommendations would you make to mike about how to sample his clients?
o alphabetize them and select every third client.
o alphabetize them in a list and select the first few.
o alphabetize them and select a few from the end of the list.
o alphabetize them in a list and select a few from the middle.

Explanation:

Question #18

A simple random sample (SRS) is defined as a sample where every possible group of the given size has an equal chance of being selected.

• The first option is too vague as "simple way" is not well - defined in statistical terms.
• The second option is incorrect because in an SRS, all groups of the specified size (in this case, size 25) must have the same chance, not just most.
• The fourth option is a convenience sample (selecting the first 25 respondents), which is not an SRS.

• Alphabetizing and selecting every third client is a form of systematic sampling. If the list is in random order (alphabetical order can be considered a random - like order for client names in most cases), systematic sampling can be a valid way to avoid bias.
• Selecting the first few (second option) is a convenience sample and can introduce bias (e.g., clients who are more eager to respond or have a certain characteristic related to being at the top of the alphabet).
• Selecting from the end (third option) or the middle (fourth option) also introduces non - random selection criteria that can lead to bias.

Answer:

Any group of 25 subjects has the same chance of being the selected sample.

Question #19