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Comparing two populations
Differences in boys and girls (gender) or age groups (e.g. different years, or children and adults) provide the basis for considering these different populations and the differences that may occur for measurement variables.
To do this, the underlying samples and populations must be well defined.
Appropriate graphical representations that can be compared are needed.
Measures of centre and spread can help decide if there is a difference in the samples that potentially reflects a difference in the populations.
The evidence collected in this process will support any conclusion about differences (or not) between the two populations, along with any uncertainty.
Investigations with measurement variables might ask if boys or girls (or children or adults):
- can stand on one foot longer with their eyes closed
- have longer signatures
- have longer arm spans (see Building Informal Inference with TinkerPlots in a Measurement Context).
Balancing act 2
The question of "How long can typical year X students stand on one foot with their eyes closed?" is extended to compare two different populations, perhaps boys and girls, or children and adults.
Signature length 2
The question of "How long is a typical year X student’s signature?" is extended to compare two different populations. This activity begins with establishing which populations are sampled and includes making predictions about larger populations.