6.1 Conducting an investigation · Unit 6 Collecting data

1 · Teaching slidesuse ← → keys

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2 · Key words

dataInformation that has been collected.

statistical questionA question you answer by collecting data that varies.

predictionWhat you expect the data to show, written before you collect it.

primary dataData you collect yourself.

secondary dataData somebody else collected.

categorical dataData that is a word or a label.

discrete dataNumerical data you count; only whole values occur.

continuous dataNumerical data you measure; any value in a range can occur.

tally chartA chart for counting in fives as the data arrives.

frequencyHow many times a value or category occurs.

class intervalA group that measurements are sorted into, such as 150 ≤ h < 160.

3 · Summary of the sectionrevise from this

A statistical question is one whose answer varies, so you need data to answer it.
Write the question and your prediction first — then you know what data to collect.
Primary data you collect yourself; secondary data somebody else collected.
Categorical data is words. Discrete data you count. Continuous data you measure.
A tally chart counts reliably in fives; the totals become the frequency column.
Group continuous data into class intervals that do not overlap and leave no gaps: 150 ≤ h < 160, then 160 ≤ h < 170.
A fair question is neutral, and its answer boxes cover every case exactly once.
A prediction that the data does not support is still a real result. Report it.