Topic 10B: Reading Research


These are the solutions for the Topic 10B Computer Lab.

1 Readings recap

No solutions required.

2 Internal validity and experimental studies: Exercises

Adapted from Dunn (2021).

2.1

1. Not ecologically valid. 2. Ethical. People understand that sometimes unexpected things happen. 3. Convenience; self-selected. However, nothing obvious to suggest the people in the study would record different accuracies than people not in the study. 4. Inclusion criteria. 5. Paired \(t\)-test. 6. Evidence in the sample that the mean difference in step-count between the two methods cannot be explained by chance: likely is a difference. 7. From the given information: Probably valid.

2.2

1. Students at that university (QUMS). 2. A random sampling method has been used, so results should be generalisable to the population (students at that university). 3. \(t\)-test comparing two means. 4. Three groups. Null hypothesis: the population mean hearing loss score is the same in all three groups. Alternative hypothesis: the mean hearing loss score is not the same in all three groups.

2.3

  1. No solution required.

  2. The six steps are:

    1. Ask the question: The POCI elements are:
      • Population: The population is people from ‘different countries’ across the world. No further inclusion or exclusion criteria is provided in the abstract, however further information can be found in Section 3 (Methods)
      • Outcome: The mean difference in BMI and various diseases, when comparing across differing levels of weekly soft drink consumption
      • Comparison: Between different levels of weekly soft drink consumption
      • Intervention: There was no intervention. The RQ’s are relational and this is an observational study.
    2. Design the study: Although not specifically stated, we know from Section 3.1 (Design) that this is a cross-sectional study.
    3. Collect the data: The data was collected from a self-administered, online survey.
    4. Describe and summarise the data: The abstract provides no summary data,
    5. Analyse the data: Although not stated, the results presented in the abstract may be based on an independent samples \(t\)-test and Chi-squared tests.
    6. Report the results: Evidence exists for a difference in BMI and various diseases when comparing different levels of soft drink consumption.

  3. The following statistical techniques and tests have been mentioned:

    • Descriptive statistics to describe and summarise data
    • Parametric tests (\(t\)-tests, ANOVA)
    • Non-parametric tests
    • Levene’s test for homogeneity of variances
    • Correlation analysis (Spearman correlation)
    • ‘regression’ (although it is not clear what the regression analysis was)
    • Chi-squared tests

We have learnt about all of these techniques in this subject except for non-parametric tests. Non-parametric tests are often used as alternative to tests such as the \(t\)-test and ANOVA when the assumptions are not met.

References

Dunn, Peter K. 2021. Scientific Research and Methodology: An Introduction to Quantitative Research in Science and Health. https://bookdown.org/pkaldunn/Book.


These notes have been prepared by Amanda Shaker. The copyright for the material in these notes resides with the authors named above, with the Department of Mathematics and Statistics and with La Trobe University. Copyright in this work is vested in La Trobe University including all La Trobe University branding and naming. Unless otherwise stated, material within this work is licensed under a Creative Commons Attribution-Non Commercial-Non Derivatives License BY-NC-ND.