Lesson 2.2.3

2.2.3 Analysing experiments: descriptive and inferential statistics Quiz: Pearson Edexcel Psychology, Unit 2

20 questions

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Lesson 2.2.3, Analysing experiments: descriptive and inferential statistics: 20 multiple choice questions for the Pearson Edexcel Psychology (9PS0), Unit 2: Cognitive psychology, written with Revision Ninja.

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The 20 questions

  1. What is the mean of the recall scores 4, 6, 6, 8 and 11?

    • 8
    • 7
    • 6
    • 11
  2. What is the median of the recall scores 3, 5, 7, 7, 10 and 12?

    • 10
    • 7.5
    • 7
    • 9
  3. What is the range of the recall scores 3, 5, 7, 7, 10 and 12?

    • 9
    • 10
    • 7
    • 12
  4. Which measure of central tendency is best suited to ordinal data such as ranked scores?

    • The mean, since it requires equal intervals between ranks to be calculated and interpreted correctly
    • The median, since it uses the middle position of ordered data without requiring equal intervals
    • The standard deviation, since it describes the spread of the ranks around the mean of the group
    • The range, since it describes the difference between the highest and lowest ranks in the data set
  5. What is the percentage of 18 correct answers out of 24 questions?

    • 80%
    • 72%
    • 75%
    • 67%
  6. Which inferential test is non-parametric and used for an independent groups design?

    • The Mann-Whitney U test
    • The Pearson correlation, which is used to test the strength of a relationship between two continuous variables
    • The Wilcoxon signed-ranks test, which is used for repeated measures designs with related scores
    • The t-test, which is a parametric test that assumes the data are normally distributed in the population
  7. Which inferential test is non-parametric and used for a repeated measures design?

    • The chi-squared test, which is used for categorical frequency data in a contingency table of counts
    • The Wilcoxon signed-ranks test
    • The Mann-Whitney U test, which is used for independent groups designs with unrelated scores
    • The Spearman's rho, which is used to test the strength of a correlation between two sets of ranks
  8. What does a significance level of p≤.05 mean?

    • There is a 5% probability that the alternative hypothesis is true, so the result is weakly supported
    • There is a 5% or lower probability that the result occurred by chance if the null hypothesis is true
    • The sample is 5% of the population, so the result can be generalised to the population with confidence
    • There is a 95% probability that the null hypothesis is true, so the result is almost certain to be correct
  9. A researcher's result has p = .03. Which conclusion is appropriate at the p≤.05 level?

    • The result is significant at p≤.05, so the null hypothesis can be rejected
    • The result proves the alternative hypothesis is true, so no further tests are needed in the study at all
    • The result is significant at p≤.01, so the null hypothesis is proven to be false with complete certainty
    • The result is not significant at p≤.05, so the null hypothesis must be accepted as true for the population
  10. What is a Type I error?

    • Rejecting the null hypothesis when it is actually true, a false positive
    • Accepting the null hypothesis when it is actually false, a false negative in the study's conclusions
    • Using a sample that is too small to show any significant difference between the conditions in the study
    • Using a non-parametric test when a parametric test should be used because the data were normal
  11. What is a Type II error?

    • Recording data with a measurement error, which makes the scores inaccurate across all participants
    • Using the wrong sampling method, which leads to a sample that does not represent the population at all
    • Accepting the null hypothesis when it is actually false, a false negative
    • Rejecting the null hypothesis when it is actually true, a false positive in the conclusions of the study
  12. When should a one-tailed test be used?

    • When the sample is very large, so that the chance of finding a significant result is always reduced
    • When the data are normally distributed, so that a parametric test can be used in every case of research
    • When the hypothesis predicts the direction of the difference, based on clear previous research
    • When the researcher has no prediction about the direction of the difference, so that any change is tested
  13. Which statement about a normal distribution is correct?

    • It is symmetrical, with the mean, median and mode at the centre of the distribution
    • It is uniform, with every score occurring the same number of times across the whole distribution
    • It is skewed to the right, with the mode always lower than the mean and median in the distribution
    • It is skewed to the left, with the mode always higher than the mean and median in the distribution
  14. Which statement about a skewed distribution is correct?

    • Its mean is pulled towards the direction of the tail, away from the mode
    • Its range is always zero, since the scores in a skewed distribution are always identical to each other
    • Its mean, median and mode are always identical, so skew has no effect on any measure of central tendency
    • Its mode is always the largest value in the data set, with a long tail trailing back towards the mean
  15. A researcher finds the Mann-Whitney U value is smaller than the critical value at p≤.05. What should she conclude?

    • The result is not significant, so the null hypothesis must be accepted as true for the population
    • The result is not significant because the sample is too small for any test to be valid at all
    • The result is significant, so the null hypothesis can be rejected at that level
    • The result is significant at p≤.01, which is a stronger level than p≤.05 in every case
  16. Which of these is a benefit of using a descriptive statistic before an inferential test?

    • It proves that the hypothesis is true, so no inferential test is needed to confirm the result in any study
    • It removes the need for any inferential test, because the descriptive values show the answer directly
    • It summarises the data and helps check whether the results make sense before testing them
    • It guarantees that the result is significant, so a significance test is no longer needed in the report
  17. A researcher reports a Mann-Whitney U test result and a Wilcoxon test result for the same data. What is the likely error?

    • No error, since both tests are correlations and are used to measure the strength of relationships in data
    • The wrong test has been used for the design, since Mann-Whitney is for independent groups and Wilcoxon for repeated measures
    • No error, since both tests are parametric and both assume that data are normally distributed in the population
    • No error, since both tests are for repeated measures and can be used interchangeably with the same data
  18. Which of these is the best reason for checking the critical value tables?

    • To decide whether an observed test value is significant at a chosen level of probability
    • To calculate the mean of the data before any statistical test is carried out on the scores in the study
    • To decide which participants should be removed from the sample before the analysis begins in the study
    • To decide which graph to draw to display the frequency of each category in the results section
  19. Which graph is most appropriate for showing the distribution of continuous recall scores?

    • A histogram, with bars touching to show the frequency of scores across a continuous range
    • A bar chart with gaps between bars, which is used for displaying categories such as favourite colours
    • A scatter plot, which is used to show the relationship between two variables for each individual participant
    • A pie chart, which is used to show the proportion of a whole when the categories do not overlap at all
  20. Which test would be used for an independent groups design with ordinal data?

    • Pearson's r, which is a parametric test of correlation that assumes normally distributed continuous data
    • Spearman's rho, which is a test of correlation between two sets of data rather than a test of difference
    • Mann-Whitney U, which is a non-parametric test of difference for independent groups
    • Wilcoxon signed-ranks, which is a non-parametric test of difference for repeated measures designs

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