HOW TO
SET UP AN APPROPRIATE SCALE ON A GRAPH
1. Look at your data. Find the largest number that will be plotted
on the x axis.
2. Count the number of boxes there are across
the x axis. (If you are using graph
paper, count the number of boxes from where the y axis will be to close to the
right side of your paper.)
3. Divide the largest number on the data table
by the number of boxes. (Usually, this
will be a number with a lot of places to the right of the decimal point. To make it easier, you should probably round up. The number you round to should be what each
line represents.)
4. Find the largest number among your data to be
plotted on the y axis.
5. Count the number of boxes on the y axis.
6. Divide the largest number on the data table
by the number of boxes. Round up as
appropriate.
EXAMPLE: I am using the graph paper that is linked to
the Periodic Trends in Atomic Radius activity.
On the x
axis, atomic number is plotted. The
highest atomic number given on the data table is 54.
The number
of boxes across the paper is 30.
54 divided
by 30 is 1.8. I am going to have each line
represent 2. (When I graph my data,
there will be points that are in the middle of boxes. This is OK.)
On the y
axis, atomic radius is plotted. The
highest atomic radius given on the data table is 2.16.
The number
of boxes down the page is 40.
2.16
divided by 40 is 0.054. I am going to
have each line represent 0.06.
By setting
up scales for your graph this way, you use most of the graph. It also allows for the most accurate graphing
of your data. Doing this is especially
important in Physics.