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Data Types, Primary/Secondary Sources, Reliability and Validity

Before you collect data you have to know what kind it is and where it comes from. Learn the types of data, the difference between primary and secondary sources, and what reliability and validity mean.

⏱️ 16 min 🎯 14 activities
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What you'll cover

Before you collect data

Statisticians do not just gather numbers. First they decide what KIND of data they are dealing with, and they judge where the data comes from. This module covers the types of data, the difference between primary and secondary sources, and two important qualities, reliability and validity.

Types of data

Four terms describe the kinds of data. Learn them first.

Primary or secondary?

Data is also grouped by where it comes from.

Match the data type

  • Qualitative
  • Quantitative
  • Discrete
  • Continuous
  • Data made of categories or words
  • Data made of numbers
  • Counted in whole values, like a number of goals
  • Measured and can take any value in a range

Discrete or continuous?

The number of goals scored in a match is an example of which type of data?

  • Discrete
  • Continuous
  • Qualitative
  • Secondary

Reliability or validity?

These two words are easy to mix up. Reliability is the consistency of results: if you repeat the method, you get the same result. Validity is different: it means the method measures what it is meant to measure. A method can be reliable without being valid.

Match the term

  • Primary data
  • Secondary data
  • Reliability
  • Validity
  • Data you collect yourself for your own purpose
  • Data already collected by someone else
  • The consistency of results when repeated
  • Measuring what it is meant to measure

Which are quantitative?

Which TWO of these would give quantitative data? Choose all that apply.

  • The height of each pupil
  • The number of pets each pupil has
  • The favourite colour of each pupil
  • The eye colour of each pupil

From raw to grouped

Put the steps of grouping data in order.

  • Collect the raw data
  • Sort the values into order
  • Choose suitable class intervals
  • Group the data into a frequency table

Complete the terms

Data that is counted in whole values is _____ data. Data that is measured and can take any value in a range is _____ data. Data you collect yourself is _____ data. A method that gives the same result each time it is repeated is _____. A method that measures what it should measure is _____.

discrete continuous primary reliable valid qualitative quantitative secondary census ordinal

Spot the continuous data

Tap the TWO examples of continuous data.

  • The height of a plant in centimetres
  • The time taken to run a race
  • The number of students in a class
  • The favourite subject of each pupil

Which quality?

A method gives the same result every time it is repeated. Which quality does it have?

  • Reliability
  • Validity
  • Primary
  • Discrete

Classify the data

For each situation, choose the correct type of data.

  • A researcher records the exact weight of each parcel. What type of data is this?
  • A shop counts the number of items sold each day. What type of data is this?
  • A student uses figures already published by the government. What type of data is this?

Explain the differences

Explain the difference between reliability and validity, and between primary and secondary data. Give an example of each kind of data.

  • Explain what reliability means and what validity means
  • Explain the difference between primary and secondary data
  • Give one example of primary data and one of secondary data