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18.5 Chapter summary

  • Data handling means gathering and recording information, and then presenting it in a way that can be understood easily and used by other people.
  • The population is the entire group being studied.
  • A sample is a subset of the population that represents the population.
  • Bias is the over- or underestimating of an outcome in a data set.
  • Tallies are a way of counting by drawing a short vertical line to record each item.
  • The frequency is how many times an event or observation occurred.
  • We can organise data by grouping data points into intervals (classes).
  • Intervals are a range of values that are consistently defined and equal in size.
  • The mean is the sum of a set of values, divided by the number of values in the set.
  • The median of a data set is the value in the central position, when the data set has been arranged from the lowest value to the highest value.
  • The mode of a data set is the value that occurs most often in the set.
  • The mode can also be described as the most frequent or most common value in the data set.
  • A bimodal data set has two modes.
  • The range of a data set is the difference between the maximum value and the minimum value in the set.
  • An extreme value (outlier) is a number in the data set that is not typical of the rest of the set. It is usually a value that is much greater or much smaller than all the other values in the data set.