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Practice

Three kinds of tasks: hand calculations with new numbers, method selection from a study design, and interpreting Linza results calculated from synthetic data. Answers are not saved.

Calculate it yourself

Work it out on paper or in your head, then check your answer. Choose “New numbers” to get another set.

Data: 9, 10, 6, 11, 6, 6

Find the mean. Round to 2 decimal places.

Tasks solved: 0

Choose a method for each study

For each description, choose a suitable method. Consider the design: whether observations are independent, what was measured and how many groups there are.

Correct: 0 of 13

  1. Strength is compared for 10 specimens from batch A and 12 from batch B. Spread differs noticeably between batches.
  2. Weight was measured in 15 people before and after a one-month diet program.
  3. Participants in two independent groups rated interface usability on a scale from 1 to 5.
  4. Yield of three varieties is compared on 8 independent plots each. Data look roughly normal with similar spread.
  5. Reaction time in four groups of 6 people. Distributions are strongly skewed with outliers.
  6. Sixteen participants have a measurement taken before and after exercise. Differences are roughly symmetric, but the data include strong outliers. Which paired rank test fits?
  7. Three reviewers rate the same samples on an ordinal scale. Which rank method accounts for the matched samples?
  8. Twelve plots received different fertiliser doses and yield was measured. The points lie roughly along a straight line.
  9. A 2 × 2 table: smoker or not, and disease or not. One cell contains only 2 people.
  10. Time to failure of lamps from two makers. The test stopped at 1000 hours while some lamps still worked.
  11. Reaction yield was measured at three temperatures and with two catalysts, each run on a new sample.
  12. The same mice were weighed at four time points; some mice miss one measurement.
  13. Cell growth was measured at ten drug concentrations from 0.01 to 100. The response falls along an S-shaped curve.

Questions about calculated results

Open a synthetic example in Linza, find the requested result and check your answer. Answer keys come from verified calculations by the scientific engine.

Solved: 0 of 8. Progress is not saved and resets when you reload this page.

  1. Task 1 · Does a new formulation make a stronger material?

    What is the mean strength of the new formulation, MPa?

    Open the example in Linza Opens in a new tabTopic: Typical value and spread
    Hint

    Analyses, the descriptive statistics table, the new formulation row, the Mean column.

  2. Task 2 · Does a new formulation make a stronger material?

    What is the upper bound of the 95% CI of the mean difference (standard minus new)?

    Open the example in Linza Opens in a new tabTopic: Effect size and power
    Hint

    Analyses, test details: the line with the 95% CI of the mean difference. The bound is negative.

  4. Task 4 · How did scores change after training?

    How many degrees of freedom does the paired t-test have?

    Open the example in Linza Opens in a new tabTopic: Comparing two groups
    Hint

    Test details show df. Recall the paired test formula: df = n − 1, where n is the number of pairs.