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Learn about different types of variables, how to identify them, and examples for categoric, ordered, discrete, and continuous variables in experiments. Enhance your practical work skills!
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Learning Objectives You should learn : • About different types of variables, • How to identify them when doing your practical work.
Can you remember what is meant by… …an independent variable? …a dependent variable? …a control variable? Revision of variables
Revision of variables Summary: The independent variable is the one that you change or select. The dependent variableis the one changes as a result, and that you measure. The control variables must not change, so that it is a fair test.
Types of variables • There are 4 other types of variables that you may meet. • Their names are: • Categoric • Ordered • Discrete • Continuous • We’ll look at two examples of each one.
Categoric variables These have word labels. Example 1 In this experiment on conduction of heat: The Categoric variables are: copper, iron, glass
Categoric variables These have word labels. Example 2 In this experiment to find the resistance of wires: The Categoric variables could be: copper wire, iron wire, steel wire, etc
Ordered variables These are categoric variables that can be ranked, in an order. Example 1 In this experiment to find the resistance of wires: The Ordered variables could be: thick copper wire, thinner copper wire, very thin copper wire.
Ordered variables These are categoric variables that can be ranked, in an order. Example 2 In an experiment to investigate a falling parachute: The Ordered variables could be: large parachute, medium parachute, small parachute.
Discrete variables These variables can only have whole number values, 1, 2, 3,… Example 1 In an experiment to investigate the stretching of a spring: The discrete variables are: 1 weight, 2 weights, 3 weights, …
Discrete variables These variables can only have whole number values, 1, 2, 3,… Example 2 In an experiment on the cooling of an insulated beaker: The discrete variables are: number of layers of insulation = 1 layer, 2 layers, 3 layers, …
Continuous variables These variables can have any numerical value. Example 1 In this experiment to investigate the stretching of a spring: The continuous variable is: length of the spring = 15.1 cm, 15.5 cm, 15.9 cm …
Continuous variables These variables can have any numerical value. Example 2 In this experiment to investigate the cooling of water: The continuous variable is: the temperature of the water = 70.6oC, 68.4oC, 66.2oC …
In summary • Categoric • These have word labels. • Ordered • These categoric variables can be ranked, in an order. • Discrete • These can only have whole number values. • Continuous • These can have any numerical value.
Learning Outcomes You should now: • Understand the difference between • - Categoric, • - Ordered, • - Discrete, and • - Continuous variables • Be able to identify these variables when doing your practical work.