What does the box in a box plot mean?
A boxplot is a way to show a five number summary in a chart. The main part of the chart (the “box”) shows where the middle portion of the data is: the interquartile range. At the ends of the box, you” find the first quartile (the 25% mark) and the third quartile (the 75% mark).
How do you read box plots?
The median (middle quartile) marks the mid-point of the data and is shown by the line that divides the box into two parts. Half the scores are greater than or equal to this value and half are less. The middle “box” represents the middle 50% of scores for the group.
What are the boxes in a graph called?
A box and whisker plot—also called a box plot—displays the five-number summary of a set of data. The five-number summary is the minimum, first quartile, median, third quartile, and maximum. In a box plot, we draw a box from the first quartile to the third quartile. A vertical line goes through the box at the median.
What does a box plot show about variability?
Short boxes mean their data points consistently hover around the center values. Taller boxes imply more variable data. That’s something to look for when comparing box plots, especially when the medians are similar. Wider ranges (whisker length, box size) indicate more variable data.
How do you interpret outliers in box plots?
The lower quartile value is the median of the lower half of the data. The upper quartile value is the median of the upper half of the data. An extreme value is considered to be an outlier if it is at least 1.5 interquartile ranges below the first quartile, or at least 1.5 interquartile ranges above the third quartile.
How do you make a Boxplot with two sets of data in R?
- If you’d like to compare two sets of data, enter each set separately, then enter them individually into the boxplot command. x=c(1,2,3,3,4,5,5,7,9,9,15,25) y=c(5,6,7,7,8,10,1,1,15,23,44,76) boxplot(x,y)
- You can easily compare three sets of data.
- You can use the argument horizontal=TRUE to lay them out horizontally.
How do you find the lower and upper adjacent values?
The upper outer fence (UOF) is defined as the threshold located at Q3 + (3*IQR). The lower outer fence (LOF )is defined as the threshold located at Q1 – (3*IQR). The outlier percentage is the count of outliers divided by the total count for each category.
What does outliers mean in boxplot?
An extreme value is considered to be an outlier if it is at least 1.5 interquartile ranges below the first quartile, or at least 1.5 interquartile ranges above the third quartile.