Calculate statistical measures to compare data.
3.4.1 D1a
Basic foundation content | Additional foundation content | Higher content only |
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Calculate averages for discrete and grouped data: - mode
- median
- arithmetic mean.
| | Calculate averages for discrete and grouped data: - weighted mean
- geometric mean
- mean seasonal variation.
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Notes: use of the term ‘mean’ should be assumed to be arithmetic mean in exams, unless the word geometric is used.
3.4.2 D1b
Basic foundation content | Additional foundation content | Higher content only |
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| | Justify the rationale for selecting appropriate types of average in context. | |
Notes: students should understand when the geometric mean may be more useful than the arithmetic mean.
3.4.3 D2
Basic foundation content | Additional foundation content | Higher content only |
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Determine skewness from data by inspection. | | Determine skewness from data by calculation. |
Notes: formulae for skewness will be given when required.
3.4.4 D3a
Basic foundation content | Additional foundation content | Higher content only |
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Calculate different measures of spread: | In addition those in the basic foundation content, calculate the following measures of spread: - interquartile range
- percentiles.
| In addition those in the foundation content, calculate the following measures of spread: - interpercentile range
- interdecile range
- standard deviation.
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Notes: when calculating quartiles data sets will have values where is one less than a multiple of 4.
3.4.5 D3b
Basic foundation content | Additional foundation content | Higher content only |
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Identify outliers by inspection. | | Identify outliers by using appropriate calculations. |
- more than 1.5 interquartile ranges from the relevant quartile
- more than 3 standard deviations from the mean.
3.4.6 D4
Basic foundation content | Additional foundation content | Higher content only |
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Identify trends in data through inspection. | Identify trends in data by calculation of 4 point moving averages. | Identify trends in data by calculation of moving averages which have been determined to be appropriate. |
3.4.7 D5
Basic foundation content | Additional foundation content | Higher content only |
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Determine line of best fit by eye. | Determine line of best fit by drawing through a calculated double mean point . | Determine line of best fit by using the equation of the regression line. |
Notes: double mean points, when used, should be plotted.
3.4.8 D6
Basic foundation content | Additional foundation content | Higher content only |
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| | | Apply formula to determine Spearman’s rank correlation coefficient. Values found using calculator functions will be permissible. |
Notes: the formula will be given in the question.
3.4.9 D7
Basic foundation content | Additional foundation content | Higher content only |
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Use collected data to calculate estimates of probabilities. | | |
