A town hosts an Arbor Day celebration. Each of the 105 families attending gets to choose a sapling to take home as they leave. Michelle and Ari each design surveys in order to determine the average height of the saplings. Michelle samples the first 20 families leaving the celebration. Ari samples every fifth family leaving the celebration. Which best explains which student’s sample is likely to produce more valid results?

2 Answer

  • Ari have more valid results than Michelle. It is because, if you see at the collection of numbers, then Michelle is concentrating only on first 20 numbers, their median could be very different from the rest of the data.

    But Ari is collecting close value of median of whole data, in that situation, he will hit the most correct /Accurate results

    Hope this helps!
  • You can use the fact that the core moto of sampling is to help predict the population parameters.

    The sampling done by  Ari is better.

    Why do we do sampling?

    We do sampling so that we don't have to work on entire population of items but only on that sample in a way that we can predict information about population.

    Most of the times, it isn't possible in real world to work on entire populations. Samples come out for rescue by assumptions that they will have some properties of the population pertained in them.

    Thus, the sample should be taken out such that it includes data of the population as much  as it can in unbiased way so as to imitate population.

    How to choose whose sampling was better in this condition?

    • Since Michelle picked first 20 families, there is high chances of skewed information holding sample to come out. It is because it may be that first leaving families are not well interested in the program and thus do not have good height saplings. Or many such possibilities creeps in when working on skewed(one sided and not evenly spread).
    • The sampling done by Ari was better since it was more spread to all people uniformly, thus, the sample coming out will have information of the population well contained in it, in the way it is contained in the population.


    The sampling done by  Ari is better.

    Learn more about sampling techniques here: