Identify and compare sampling techniques

A question is this sub-type if and only if it asks the student to name/state the sampling method being used, compare advantages/disadvantages of different sampling techniques, or explain differences between sampling approaches such as census versus sample or stratified versus simple random sampling.

4 questions

OCR MEI AS Paper 2 2023 June Q12
12 Doctors are investigating the weights of adult males registered at their surgery. One week they collect a sample by noting the weight in kilograms of all the adult males who have an appointment at their surgery.
  1. State the sampling method they use.
  2. Explain why this method will not generate a simple random sample of all the adult males registered at their surgery. They represent the data using a histogram.
    \includegraphics[max width=\textwidth, alt={}, center]{82438df0-6550-4ffd-92d8-3c67bec59a6b-09_1166_1243_726_233} An incomplete frequency table for the data is shown below.
    Weight in kg\(50 -\)\(65 -\)\(75 -\)\(80 -\)\(90 -\)\(100 - 120\)
    Frequency8
  3. Complete the copy of the frequency table in the Printed Answer Booklet. One of these patients is selected at random.
  4. Determine an estimate of the probability that he weighs either less than 60 kg or more than 110 kg .
  5. Explain why your answer to part (d) is an estimate and not exact.
OCR MEI AS Paper 2 2021 November Q11
11 James is investigating the amount of time retired people spend each day using social media. He collects a sample by advertising in a local newspaper for people to complete an online survey.
  1. State
    • the name of the sampling technique he is using,
    • one disadvantage of using this technique.
    James processes his data in order to draw a histogram. His table of results is shown below.
    Time spent using social media in minutes\(0 -\)\(15 -\)\(30 -\)\(60 -\)\(120 - 240\)
    Number of people per minute12.214.08.47.33.1
  2. Show that the size of the sample is 1455 .
  3. Calculate an estimate of the probability that a retired person spends more than an hour per day using social media.
Edexcel S2 Q1
  1. (a) Briefly describe the difference between a census and a sample survey.
    (b) Illustrate the difference by considering the case of a village council which has to decide whether or not to build a new village hall.
Given that the council decides to use a sample survey,
(c) suggest suitable sampling units.
Edexcel Paper 3 2018 June Q4
  1. Charlie is studying the time it takes members of his company to travel to the office. He stands by the door to the office from 0840 to 0850 one morning and asks workers, as they arrive, how long their journey was.
    1. State the sampling method Charlie used.
    2. State and briefly describe an alternative method of non-random sampling Charlie could have used to obtain a sample of 40 workers.
    Taruni decided to ask every member of the company the time, \(x\) minutes, it takes them to travel to the office.
  2. State the data selection process Taruni used. Taruni's results are summarised by the box plot and summary statistics below.
    \includegraphics[max width=\textwidth, alt={}, center]{65e4b254-fb7b-45c2-9702-32f034018193-10_378_1349_1050_367} $$n = 95 \quad \sum x = 4133 \quad \sum x ^ { 2 } = 202294$$
  3. Write down the interquartile range for these data.
  4. Calculate the mean and the standard deviation for these data.
  5. State, giving a reason, whether you would recommend using the mean and standard deviation or the median and interquartile range to describe these data. Rana and David both work for the company and have both moved house since Taruni collected her data. Rana's journey to work has changed from 75 minutes to 35 minutes and David's journey to work has changed from 60 minutes to 33 minutes. Taruni drew her box plot again and only had to change two values.
  6. Explain which two values Taruni must have changed and whether each of these values has increased or decreased.