Box plots are visual illustrations of this information.
A box plot provides a visual approximation of the distribution of a data set since each segment of the chart contains one quarter, or of the data. Note that the center of the data lies inside the box. The further apart the segments are, the greater the spread is for that quarter of the data.
Thanks a Latte Café measured the temperature of cappuccinos. The box plot below shows the results in F.
A good cappuccino, according to the experts, has a temperature between F and F. Approximately how many of the cappuccinos could be considered "good"?
Sometimes, the data will be given in ascending order. When it is not, it's necessary to order the data so the quartiles can be found. With an ordered data set, the minimum and maximum are easily identifiable. Here, the minimum is and the maximum is These are marked above a number line with a line segment, indicating the range.
Since there are values, the median is the mean of the numbers at the th and th position. Now, the median can be determined by calculating the mean of and The median is This is marked as a vertical line segment in the range. Remember that the line for the median falls inside the box.
The quartiles are marked as the sides of the box plot. Now the box plot is complete.