See also interquartile range and quartiles. Values higher than Q3+1.5xIQR or lower than Q1-1.5xIQR are considered outliers and are plotted above the top whisker or below the bottom whisker. The ends of the whiskers are marked by two shorter horizontal lines. The vertical lines protruding from the box extend to the minimum and the maximum values of the data set, as long as these values are not outliers. The horizontal line inside the box is the median. Therefore the vertical width of the central box represents the inter-quartile deviation. The bottom side of the box represents the first quartile, and the top side, the third quartile. The box plot is also referred to as box and whisker plot or box and whisker diagram Elements of the box plot What is a box plotĪ box plot is a diagram that gives a visual representation to the distribution of the data, highlighting where most values lie and those values that greatly differ from the norm, called outliers. These measures are displayed to the left of the chart.For more details on the dispersion of the data set, you may click on the More dispersion data link located on the left of the plot. When you submit your data, the server calculates the measures that will be used to plot the diagram. To clear the graph and enter a new data set, press "Reset".
You may also copy and paste data from another window such as an open document, spreadsheet pdf file or another web page. You do not need to specify whether the data is from a population or a sample. Individual values may be entered on separate lines or separated by commas, tabs or spaces. You must enter at least 4 values to build the box plot. For easy entry, you can copy and paste your data into theentry box from Excel. The descriptive statistics calculator will generate a list of key measures and make a histogramchart to show the sample distribution.
If you prefer the spoken word over the written word, check out our YouTube channel, and this tutorial showing how to create a histogram in SPSS.This page allows you to create a box plot from a set of statistical data: Enter your data as a string of numbers, separated bycommas. You should now be able to create a histogram within SPSS using one of its legacy tools. If you want to save your histogram, you can right-click on it within the output viewer, and choose to copy it to an image file (which you can then use within other programs). You’ll notice that SPSS also provides values for mean and standard deviation. The y-axis (on the left) represents a frequency count, and the x-axis (across the bottom), the value of the variable (in this case Height). The SPSS output viewer will pop up with the histogram that you’ve created.
You’re now ready to create the histogram. We suggest you also tick the Display normal curve option, though this is optional. You can do this by selecting the variable, and then clicking the arrow (as above). You need to select the variable on the left hand side that you want to plot as a histogram, in this case Height, and then shift it into the Variable box on the right. The simplest and quickest way to generate a histogram in SPSS is to choose Graphs -> Legacy Dialogs -> Histogram, as below. For example, are there more heights at the top end than at the bottom end – in other words, is the distribution skewed? A histogram will go some way to answering this question. We want to know how the frequency of heights is distributed. The variable we’re interested in out of the three you can see here is height.
Histogram will appear in SPSS output viwerĪs per usual with these quick tutorials, the starting assumption is that you have already imported data into SPSS, and you’re looking at something a bit like this.Select “Display normal curve” (recommended).Drag variable you want to plot as a histogram from the left into the Variable text box.Click Graphs -> Legacy Dialogs -> Histogram.