GCSE: Data Handling
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- 1 If one of the variables is time, then a line graph is normally the most appropriate choice.
- 2 Always have a constant scale along the axis, this will allow you to see the relationships in the data.
- 3 When asked to give an interpretation, it means to state what is obvious about the graphs. For example, the sale of umbrellas increases when rainfall increases.
- 4 When drawing a pie chart, turn the amounts into fractions, if there are 100 animals and 15 cows. We have 15/100, put this into the calculator and multiply the answer by 360. This is the amount of degrees for the cow section.
- 5 Bar charts must have gaps between each bar otherwise it is not a correct bar chart.
Averages and speed
- 1 There are three types of average mean, mode and median.
- 2 The mean is the sum of all the values divided by the amount of values. The median is the middle value and the mode is the value that occurs the most.
- 3 There are two main types of spread, inter-quartile range and range. If the range or inter-quartile range is big compared to the data then the data has a large spread.
- 4 The inter-quartile range is the upper quartile minus the lower quartile; the range is the highest value minus the lowest value.
- 5 Mean and range are affected by outliers. In a class, the teacher is older than the students, so the mean and range would be affected by the teacher’s age; therefore the mean and range are not very accurate measures. The inter-quartile range and median would be more appropriate.
What is probability?
- 1 Probability is always between the values 0 and 1. If something has the probability of 0 it is impossible, if something has the probability of 1, it is certain.
- 2 Finding probabilities of 1 and 0 are very difficult. Elvis Presley crashing a spaceship into the Loch Ness monster has a probability of about 0.0000000001, but it isn’t quite 0. However, scoring a 7 on a normal dice has a probability of 0.
- 3 In a scenario, the different probability of all the outcomes will add up to 1.
- 4 Scoring a “2” on a normal unbiased dice has a probability of 1/6. This doesn’t mean that every 6 throws you score a “2”. This means that if you rolled the dice 6 million times, you would expect to score about 1 million “2’s”.
- 5 Experimental probability is only reliable after a lot of tests, and it can always be improved by doing more tests.
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