C1aL7 and 8 Strength of Concrete.

Key Words

Variable: A part of the experiment that you could change, e.g. the size of the beaker or the amount of substance.

Dependent Variable: The variable you will measure, e.g. change in temperature or the time something takes. This variable is plotted on the vertical axis of a graph.

Independent variable: The variable you deliberately changed, e.g. concentration of acid or size of current. This variable is plotted on the horizontal axis of the graph.

Fair test: Changing only 1 variable and keeping all the other variables the same. This means you are only testing the effects of one variable, e.g. keep the volume of water the same.

Precision: How accurate the measuring device is, e.g. do the weighing scales go to 2 decimal places? 12.6g is less precise than 12.57g or 82ºC is less accurate than 82.39ºC.  Precision can be improved by using better equipment, or a better range or scale.

Accuracy: How correctly the operator reads the equipment. Saying it’s about a minute is not as accurate as saying 62 seconds. You can improve accuracy by checking your reading with someone else. Take care writing down your results in your table, e.g. writing 3.62 instead of 3.26.

Reliability: This is how sure you are that your data are correct. You can improve reliability by repeating the experiment and taking an average of the results.

Anomalous results: These are results that do not fit the pattern of all the other results.

Categoric Variable - Variable that arises though different things, like different animals, e.g. woodlice, fleas, aphids.

Discrete variable - variable that goes up in whole numbers, like number of passengers in a car.  You can't have 1/2 a passenger.

Continuous variable - can have any value, e.g. 1.24, 2.0, etc.