As part of a statistics project, Andrea would like to collect data on household size in her city. To do so, she asks each person in her statistics class for the size of their household, and reports that her sample is a simple random sample. However, this is not a simple random sample. Which of the following are valid reasons for why this is not a sample that is appropriate for this research question Why?

Charlie did not use any randomization; he took a convenience sample.

Charlie did not use a random number table to randomize the order in which he collected the students' responses, so the sample cannot be random.

In this investigation of household size, each household represents a case. Charlie incorrectly sampled individuals instead of households.

The first question we need ask is whether his classmates make up the population of the city? Or does it mean that his classmate will give unbiased representation of the entire city? Because we are certain there are many other schools within the city of interest. Less assume he can do that, what will happen to all other schools? These are many other factors rendered his choice of sampling inappropriate for this study.

Therefore, the process is not random but convenience sample, even though they might give information about their various household sizes, it might not give the true picture of the city he is trying to investigate.

The best approach should have been a probability sampling techniques, preferably a systematic random sampling approach. If he has followed this process of sample selection, it will give a more reliable and well representative sample to determine the households size in the city of his interest.