![]() The left edge of the box represents the lower quartile it shows the value at which the first $25$% of the data falls up to. This shows that $50$% of the data lies on the left hand side of the median value and $50$% lies on the right hand side. The line splitting the box in two represents the median value. ![]() Interpreting a boxplot can be done once you understand what the different lines mean on a box and whisker diagram. These can be displayed alongside a number line, horizontally or vertically. It is a useful way to compare different sets of data as you can draw more than one boxplot per graph. The shape of the boxplot shows how the data is distributed and it also shows any outliers. The smaller it is the less is the variation.Contents Toggle Main Menu 1 Definition 2 Reading a Box and Whisker Plot 2.1 Video Examples 3 Constructing a Box and Whisker Diagram 4 Worked Example 4.1 Video Example 4.2 Common Mistakes 5 Workbook 6 Test Yourself 7 External Resources DefinitionĪ box and whisker plot or diagram (otherwise known as a boxplot), is a graph summarising a set of data. The length of the plot corresponds to the measure of variation of the data set. This box-and-whiskers plot separates the data into quarters with the same number of data points in each par. Then we extend the whiskers from each quartile to the upper and lower extremes. The box has its sides at the LQ and the UQ and we display the median by drawing a line. To draw a box-and-whiskers plot begin by marking all the above mentioned values. The endpoints of the whiskers are the upper and lower extremes. It includes a box whose sides are at the LQ and the UQ with a line drawn somewhere in the middle corresponding to the median. The box-and-whiskers plot is drawn on a number line. Now we're going to introduce a second kind of plot namely the box-and-whiskers plot. It's hard to get a visualized measure of the variation when using the stem-and-leaf plot. The median is at (22 + 22)/2 = 22 and is marked by a box. Here is the stem-and-leaf plot that we made earlier in this section You can use a steam-and-leaf plot to find and display the median, the LQ and the UQ. The difference between the lower quartile and the upper quartile is called the interquartile range and corresponds to the 50% of the data points that are in the middle The LQ corresponds to 25% of your data, the median corresponds to 50% of the data and the UQ corresponds to 75% of the data. The other two values to remember are the lower quartile (LQ), which divides the lower 50% of the data points into two equally sized parts, and the upper quartile (UQ), that separates the higher 50% of the data points into two equally sized groups. The median divides the data into two equally sized parts with 50% of the data points on each side. The lowest and the highest values are our lower and upper extreme values. There are five important values to remember if you want to divide your data into quartiles. The quartiles separate the data into four equally sized parts. When we are working with a larger set of data it is much easier to separate the data into quartiles. The bigger the range the bigger is the measure of variation. When we calculate the measure of variation we first calculate the difference between the greatest and the lowest values. if we have the two number series A (10, 23, 50, 72, 90) and B (48, 49, 50, 51, 52) we can see that they both have the same median, but that there is a huge difference in variation. We then need to use the measure of variation e.g. We have already learned about the median, the mode and the mean but sometimes these don't fully describe a set of data. On the left hand side of the line we write the numbers that corresponds to the tens, 12 has 1 in the tens place and 33 has 3 in the tens place. We begin by finding the lowest and the greatest number in the data set. This could for instance be the results from a math test taken by a group of students at the Mathplanet School.ġ3, 24, 22, 15, 33, 32, 12, 31, 26, 28, 14, 19, 20, 22, 31, 15 To set up a stem-and-leaf plot we follow some simple steps.įirst we have a set of data. ![]() A stem-and-leaf plot is used to visualize data. One way to measure and display data is to use a stem-and-leaf plot.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |