Shape: The shape of a data set refers to whether or not it is symmetric or skewed.When comparing the distributions of two data sets on the same measurement using box plots, we canĬompare the “shape”, “average,” and “spread” of the data sets. Let us now summarize the key points associated with comparing data sets using box plots. Winning scores are approximately symmetric about their center. Positively skewed, more concentrated at the lower end of the scores, whereas the NBA Scores have a much larger spread around the center. While the WNBA winning scores are, on average, lower than those of the NBA, the WNBA winning In conclusion, the WNBA winning scores and those for the NBA differ in shape, average, and spread. The box, indicating that the data is more or less symmetric about the center. For the NBA data, the whiskersĪre approximately equal and there is only a small lack of symmetry on either side of the median inside The box itself is symmetric onĮither side of the median, however, so the data is not heavily skewed. Within a narrower range of values than those in the higher range. That is, the lower scores are more concentrated Is a little right (or positively) skewed. Interquartile range, we are considering the spread of the data.įor the WNBA data, the left whisker is shorter than the right. When considering the median, we are talking about the “average” When looking at whether or not a data set is skewed (or symmetric), We have compared three different statistical measures in this example: the The box is split evenly on either side of the median and the whiskers are Third possibility is that if, in a box plot, Quite high range, Mona’s distances were left (or negatively) skewed. Since half of Mona’s data were concentrated in a narrow but Lower values means that Ramy’s distances were right (or positively) skewed. In statistical terms, the concentration of half of Ramy’s data in a small range of The lower half of her distances were spread over a wider range of distances: 25% between 2 (her minimum) and
#Two box plots same graph r how to#
Let us look at some examples of how to use two box plots to compare two data sets on the same variable.
Values of the data set excluding the outliers. If there is one or more outliers in a data set, for the purpose ofĭrawing a box-and-whisker plot, we take the minimum and maximum to be the minimum and maximum Outliers, or extreme values in a data set, are usually indicated on a box-and-whisker plot by the 50% of theĭata values lie above the median and 50% lie below the median. The median sits within the box and represents the center of the data.The upper whisker covers all the data values between Q3 and the maximum value,.Q1, that is, the lowest 25% of data values. The lower whisker covers all the data values from the minimum value up to.The whiskers each cover 25% of the data values.This 50% of the data lies between Q1 and Q3 and its range is the interquartile range, The box part of a box-and-whisker plot covers the middle 50% of the values in the data set.The horizontal axis covers all possible data values.
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