The first graph that we will learn about is called a bar graph. Bar graphs are a
great way to show categorical data when you have two or more groups and a
specific number of participants in each group, the bar graph can show us numbers
and percentages. It is simple, elegant and eminently useful. Bar graphs are
particularly useful with nominal or ordinal data. You will be able to
distinguish a bar graph from a histogram, because in a bar graph, the adjacent bars
do not touch. So think about prison bars being separated from each other. The
disconnection between the bars implies that the data being plotted are not
connected to each other or ordered. For instance, blue, green, and red do not have
an order. They could be arranged as red green and blue, and furthermore you'll
notice that the vertical bars are centered over the scores on the x-axis. A
bar graph may be used with ordinal data when the data are categorical, so for
instance, if we plot year in school (freshman, sophomore, junior, senior) we
would still use a bar graph. In addition to using the chart builder, another way
to create a bar graph is through the frequencies command. Using the data set
clickers.sav, we are going to create a bar graph for gender. On the x-axis, we
will place the gender category, either male (coded one) or female (coded two). On the
y-axis, we will plot percent. Using the clickers.sav data set in SPSS, go to
analyze > descriptive statistics > frequencies. We're going to move gender
into the variables box, and then unclick display frequency tables. When we do so,
we'll get an error box. Whenever you see this it's not a problem, just click OK.
Choose the output that we want. What we want is a bar chart. So we'll click on
charts and bar charts. For the chart values, we could choose frequencies if we
want to see the raw numbers of individuals in each category, or we could
choose percentages, which is what we're going to do now. Click on continue and
okay. The output window will open. You can scroll down and find that bar chart. We
can see that approximately twice as many females participated in this research as
did males. Now if you plan to use a chart from SPSS in a thesis, a dissertation,
or a publication, there are some additional tricks that you should know
about formatting these figures. As a rule, SPSS output is never in APA style. It
must be changed to conform to APA. Several things need to change here. We
need to change the background color from grey to white, we need to remove this
word gender, we need to change these bars to gray, and we even put some percentages
on the bars. All of this begins by double clicking on the bar chart, and this opens
up the chart editor. Now in order to begin, we could go to this icon that says
"show data labels." That will open up our properties box for the data value labels.
We could also open the properties box with this icon that says show properties
window. So here in the properties box let's go to number format, and under
decimal places, let's set that to one. And then under trailing characters because
these are percentages, add a percent sign that's shift 5, and click apply. Now we
can see the percentages here in our bars. That's a good start, but we also need to
change the background we need to change that gray to something white. In order to
do that ,you click on the gray, that brings up the fill and border properties,
there's the fill, the border, let's start with a border that needs to be removed.
Click on that black for border and then this white box with the red slash, that's
transparent. It will remove of the border. Click on that, and for fill
we'll do the same thing, click on the gray (it's a little harder to see against that
gray background). When we click on transparent change the fill to
transparent as well. Now just click apply. Next we need to change the color of
these bars. They're not very attractive, and the color is not APA style. By
clicking on the bar, it brings up the preview. We can see the fill is set to
that odd greenish color, click on fill, and this time we're going to change the
color to gray. Let's use that one right there. We'll leave the border set to
black. Click apply. . . much better. Let's remove this word gender from the top, we
see it's already here on the x-axis from male and female, that's good, but we don't
need it there at the top. Click on it, select it, and delete. Ok now this chart
is really starting to look good. Now I can just close the properties box, I can
close this chart editor, by clicking here on this red circle and there is my
output. This could be exported using the export command to the desktop in a
document format, I could edit from there. Now here we have our percentages, and we
see the percentages run from 0 to 60, that's as they should be. It includes the
full range of data. But what if we wanted to have percentages run from 0 to 100? We
could do that as well. Double click, and let's go to the y axis. Select the y axis
Our minimum - leave that set to 0, and our maximum will become 100. Now our major
increments are still 20, that'll be fine, click apply, and there we go. Close that
properties window. So now we see our percentages run from 0 to 100. Close the
chart editor, and it's ready to be exported and used in a publication.