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Northern IrelandStatistics

Averages and measures of spread

3 dot points across 3 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do you find the mean, median and mode, including a weighted mean and the mean from frequency and grouped tables, and choose the best average?

Calculate the mean, median and mode, find a weighted mean and the mean from a frequency or grouped frequency table, identify the modal class, and choose the most appropriate average for the data.
A CCEA GCSE Statistics answer on measures of central tendency: the mean, median and mode, the weighted mean, the mean from frequency and grouped tables, the modal class, and choosing the most appropriate average.
11 min answer →

How do you measure the spread of data using the range, quartiles, interquartile range, percentiles and standard deviation, and compare distributions with box plots?

Find the range, quartiles, interquartile range and percentiles, calculate the standard deviation, identify outliers, and draw and compare box plots of two distributions.
A CCEA GCSE Statistics answer on measures of spread: range, quartiles, interquartile range, percentiles, standard deviation, identifying outliers, and drawing and comparing box plots of two distributions.
12 min answer →

How do you use a standardised score to compare values from two different distributions, and how do you describe the skewness of data?

Calculate and interpret standardised scores using the mean and standard deviation to compare values across different distributions, and describe the skewness of a distribution.
A CCEA GCSE Statistics answer on standardised scores: using the mean and standard deviation to standardise a value, comparing values from different distributions, and describing positive, negative and symmetrical skewness.
10 min answer →