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11.06 Surveys

Lesson

Previously, we examined censuses and surveys. We get the best data from a census because it includes the entire population. However, it's not always possible to conduct a census, so we often get our data from surveys instead.

When we take a survey it is important that the results are representative of the population. This means that the results that we get for any question we ask of the survey would be the same as if we asked it of a census. This also means that the mean, median, mode and range of the survey should be very close to the same results of the census (although getting exactly the same results is almost impossible).

If a survey is not representative, we call it biased. There are a number of potential sources of bias that we should avoid:

  • Consider who is being surveyed. If the people being surveyed do not resemble the population, the survey is likely to be biased. For example, surveying train travellers about their opinions on public transport will likely give very different results than a census of the entire population.
  • Also consider how many people are being surveyed. Asking one person's opinion will not tell you anything about anyone else's opinion. In general, the bigger the number of people being surveyed, the closer the results will be to a census.
  • Make sure that the questions being asked actually address the question at hand. For example, asking, "Do you approve of the current governing party?" does not give the same results as asking, "Will you vote for the current governing party in the next election?"
  • Avoid questions which use emotive language or might otherwise influence the results of the survey. For example, asking, "Do you watch the most popular sport, soccer?" will be biased unlike asking, "Do you watch soccer?". These are referred to as "leading questions" as they lead the person being surveyed to a particular answer.

 

Practice questions

Question 1

Consider the following questions and determine why they are inappropriate for a survey.

  1. "How many large electronic devices are in your home?"

    Question is unclear.

    A

    Emotional language.

    B

    Should be a "yes" or "no" question.

    C

    Question is too personal.

    D

    Question is unclear.

    A

    Emotional language.

    B

    Should be a "yes" or "no" question.

    C

    Question is too personal.

    D
  2. "Many people have worked incredibly hard and even died making this bridge. Do you like it?"

    Question is unclear.

    A

    Emotional language.

    B

    Should be a "yes" or "no" question.

    C

    Question is too personal.

    D

    Question is unclear.

    A

    Emotional language.

    B

    Should be a "yes" or "no" question.

    C

    Question is too personal.

    D
Question 2

Consider the survey question and the sample and determine whether the outcomes are likely to be biased or not.

  1. Rosey is asking people on her soccer team, "What's your favourite sport?"

    Biased results

    A

    Not biased results

    B

    Biased results

    A

    Not biased results

    B
  2. James randomly selected people from his school to find about the school sports. He asked "What's your favourite school sport?"

    Biased results

    A

    Not biased results

    B

    Biased results

    A

    Not biased results

    B
  3. Gwen randomly selected people from her school and asked, "The local AFL team is donating money to our school this term. What's your favourite sport?"

    Biased results

    A

    Not biased results

    B

    Biased results

    A

    Not biased results

    B
Question 3

A survey asks the following two questions with the answers displayed.

What statement can be made from the results shown?

Do you prefer reading, watching TV, or gaming?
ReadingWatching TVGaming
$23$23$21$21$35$35
Do you prefer studying, cleaning, or exercising?
StudyingCleaningExercising
$12$12$8$8$59$59
  1. Students would rather exercise than clean.

    A

    Most students would rather be exercising than gaming.

    B

    Students exercise around seven times more than they clean.

    C

    Most students don't like watching TV.

    D

    Students would rather exercise than clean.

    A

    Most students would rather be exercising than gaming.

    B

    Students exercise around seven times more than they clean.

    C

    Most students don't like watching TV.

    D

Outcomes

MA4-20SP

analyses single sets of data using measures of location, and range

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