Science Fair Computer Graphing Help Sheet
There are several types of graphs that scientists often use to display data. They include:
Pie Graphs
 Dependent variable is NOT
continuous
 Usually presents data as a
“part of a whole” or as
percentages
Bar Graphs
 Dependent variable is NOT
continuous
 There is no order to the
categories on the X-axis
 Bars typically don’t touch
 Y-axis is usually a
percentage or a frequency
(count)
Histograms
A specific type of bar graph
Dependent variable must
have a natural order that can
be grouped into defined
“chunks”
Bars must always touch
Y-axis is usually a
percentage or a frequency
(count)
Line Graphs
Scatter Plots
 Dependent variable IS
continuous
 Points are plotted using xand y-components
 The points are connected
because the observations
are NOT independent (the
next value depends on the
previous value)
 Dependent variable IS
continuous
 Points are plotted using
x- and y-components
 The points are NOT
connected because the
observations are
independent (the next
value does NOT depend
on the previous value)
 Uses a best-fit line or
curve to show
relationship
Based on these definitions, and the descriptions of the graphs above, select the type of graph that would be most
appropriate for your purpose (some descriptions may have several graph types that would be appropriate; you
only need to select one).
Graphing with Excel
Microsoft Excel can be used to enter data into a spreadsheet, which can then be used to create a chart, or graph.
The organization of the data in the spreadsheet is the most important thing, as that will determine how the graph
is created. Here are a few easy steps to create a spreadsheet and graph using Excel.
Spreadsheet and Inputting Data
You can enter data by simply clicking on one of the cells in the spreadsheet and typing in your values. Cells are
identified by the column letter and the corresponding row number: C3 or A5.
Formatting Cells
Often when data are inputted into cells, the numeric values are not
formatted the way you would like them to appear in the spreadsheet or
in graphs you will later create. The number of decimal places, along
with many other formatting options can be set by selecting the cell or cells you would like to format and
choosing Format>Cells...
When you first click on the Number tab, your cells will be listed in the Category General. This is the default
data category for a new spreadsheet. To control the decimal places, you will need to change the Category to
Number. Sometimes when numbers are entered into cells, they are changed to dates, or sometimes you will
need data to have 2 decimals. To make any formatting changes in the data, use the format cells option.
NOTE: Setting up the data correctly is the most important aspect in obtaining a graph that adequately
reflects the data.
Creating a Bar Graph With One Independent Variable
The independent variable is placed in the first column while the dependent variable
is placed in the second column. The headers at the top of each column are not
necessary, but they do help identify the variables. Do not include labels like
inches or degrees in the individual cells. Those labels should be at the top of the
column. Excel cannot graph words.
Highlight all data in the cells and start the Chart Wizard from the toolbar:
Choose the Column Chart type and the Chart subtype in the upper left corner (basic bar graph). This
chart type creates a vertical bar graph, which Excel
refers to as a Column chart. If you want to create a
horizontal bar graph, choose the Bar chart type. Click
Next when you are done.
Confirm that your Data Series are in Columns in
your spreadsheet. Your Data range should reflect
your selection of the independent and dependent data
(plus possibly your column headers) in absolute cell
references. The preview should show a pretty good
representation of what your chart will look like. Click
Next when you are done
Next you will see the place where you enter a title for the graph and enter labels for the X-axis and the Y-axis.
You will be able to see these labels right on the preview. Click Next when you are done.
Your final graph should look like this:
Creating a Bar Graph With Two Independent Variables
A multiple bar graph depicting data using two independent variables is created in the same way as a simple bar
graph. However note the additional column headings needed for additional independent variables.
Some things to note when creating this multiple bar graph:
 The first independent variable, Mammal, is still in the first column, with the dependent variable values
(Count) in columns two and three. The second and third columns represent dependent variable values at
two different levels of the second independent variable, Week.

Make sure to select all of the data when creating the graph. The Chart wizard will automatically
recognize you have a second independent variable.
Creating Pie Charts, Line Graphs, or Scatter Plots
These types of graphs can be creating using the same instructions for bar graphs on the previous pages. Just
select the appropriate chart type from the Chart Wizard (see below).
Note: Editing the chart type after this step should be similar to the example listed previously.