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[HCI Stats] Graphics (in R)

This post is based on Yatani’s wiki on HCI Stats.

  1. What is a bar plot? When would you use it?
    A bar plot shows a bar whose length (or height) is proportional to the value of the data entry.
    A bar plot can be used to show, for example, the data (in particular, the means, errors) observed from different groups.
  2. What is a box plot? When would you use it?
    A box plot visualizes “Here’s where X% of the data points go to”. For example, the median value is rendered as a bold line, then two other quantiles (forming the top and the bottom of the box) marks values under which there is 75% and 25% of the data points, respectively.
    (Another way to see it is a box plot gives a five-number summaries:
    – the smallest observation;
    – lower quantile (Q1);
    – median (Q2);
    – upper quantile (Q3);
    – the largest observation.
    A box plot can be used to show “what your data looks like” (“what range of value the data goes to”). It provides more information than a bar plot.
  3. What is a multiple dot/line plot? When would you use it?
    A multiple dot/line plot shows individual data points and/or connects them if they belong to the same group.
    It is useful to show the evolution of observation over period  (e.g., through sessions in an experiment).
  4. Create a bar plot; create a bar plot with error bars.
  5. Create a box plot. Point out the ‘five-number’ lines.
  6. Create a multiple dot/line/dot+line plot.

About Xiang 'Anthony' Chen

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