Module 03 Activity

Scenario

Describe the data honestly before testing anything about it.

What you build

A descriptive summary, a distribution chart and a paragraph in which every claim is traceable.

Steps

1. Compute the mean, median, SD, IQR and quartiles for your main measure. Where mean and median diverge, find the values responsible.
2. Choose your summary deliberately and say why — median and IQR for skewed measures, with the skew stated.
3. Group by the reporting category and carry n, the SD and the standard error through the summary.
4. Plot the distributions before testing any means. Note any bimodality, truncation or floor effect.
5. If you draw error bars, label what they are, and never judge a difference by whether two intervals overlap.
6. Write each finding with the measure, the size, the comparison and the period named.

Evidence to hand in

• The full descriptive summary.
• Your choice of central measure, with its justification.
• The grouped summary including n and se.
• The distribution chart and what it showed.
• The labelled error bars, if any.
• The findings paragraph.

Review checklist

• Mean and median are both reported where they disagree.
• Every grouped row carries n and a measure of uncertainty.
• The distributions were plotted before any test of means.
• Every error bar is labelled SD, SE or 95% CI.
• No finding claims a cause, and every one names its period.

Mark complete