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Applied Research Methods

Inferential Statistics: choosing a statistical test, parametric and non-parametric tests

  • 3 things to know
  • A2 Unit 4

Overview

Recall questions on choosing a statistical test, parametric tests and non-parametric tests.

What you need to know

Answer each one before you reveal it.

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Study

Name the three questions that between them decide which inferential test to use.

Key term

Two separate groups of participants rank ten advertisements for persuasiveness, one group after a cheerful film and one after a sad film. Which test fits?

Key term

The same participants complete a spelling test with background music and again in silence, scored out of twenty each time. Which test should be applied?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is an inferential test for?

    Model answer

    It works out how likely it is that the difference or relationship found in a sample arose by chance, so that a conclusion can be drawn about the wider population from which the sample came.

  2. 2

    Name the three questions that between them decide which inferential test to use.

    Model answer

    Whether the study seeks a difference or a relationship, whether the data are related or unrelated, and the level of measurement of the data.

  3. 3

    Fifty shoppers are recorded as either taking a leaflet or refusing one, in a store that is either quiet or busy. Which test should be used, and why?

    Model answer

    The chi-squared test, because an association is being sought between two unrelated variables and the data are frequency counts falling into categories, which is the nominal level.

  4. 4

    Each of twenty participants rates their mood before and after exercise, and only whether the rating rose or fell is recorded. Which test is appropriate?

    Model answer

    The sign test, because the design is related and the data have been reduced to the nominal level of a simple direction of change.

  5. 5

    Two separate groups of participants rank ten advertisements for persuasiveness, one group after a cheerful film and one after a sad film. Which test fits?

    Model answer

    The Mann Whitney U test, because a difference is being sought between two unrelated groups using data at the ordinal level.

  6. 6

    The same participants complete a spelling test with background music and again in silence, scored out of twenty each time. Which test should be applied?

    Model answer

    The Wilcoxon matched pairs signed ranks test, because the design is repeated measures and the scores are at least ordinal.

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