Home > Topdrawer > Statistics > Good teaching > Making informal inferences > Comparing two populations > Signature length 2
Signature length 2
Data collection
Use measurements of lengths collected in the activity Signature Length 1 or negotiate rules for collecting data (e.g. write both first and last name only, use pencil or pen, measure in mm, dominant hand, non-dominant hand).
Data representation
Create stacked dot plots for each group and a back-to-back stem-and-leaf plot.
If considering dominant and non-dominant hands, create a new variable (difference = non-dominant – dominant) to explore differences.
Create a stacked dot plot or stem-and-leaf plot for the difference variable. How is this useful?
Summarising
Compare shapes of distributions in the plots.
Compare means, medians, modes, clumps, humps, gaps and outliers.
Create and compare box-and-whisker plots for the two groups (if appropriate for year level).
Degree of certainty
Would the data look the same if two other samples were used to collect data?
Drawing an informal inference
Write a report answering the question. Include a statement about your level of confidence in the inference made and discuss the uncertainty evident in the results.