1. DETERMINE THE RANGE LIMITS OF
THE X-AXIS AND THE Y-AXIS
Examine the data set and note the minimum and
maximum values:
X-axis: ordinate (independent or
known variable): pre-specified:
time, concentration, amount added, etc.
Y-axis: abscissa (dependent or
unknown variable):
resulting measurement: weight, A660, pH, etc
(If the zero value of X or Y is important for your graph, it should
be included in the limits.)
2. DETERMINE THE LIMITS OF YOUR
GRAPH PAPER
Count the number of squares available for the X and
Y axes, leaving at least 2 squares at the bottom and sides, and 9
squares at the top.
Graph-lined composition notebooks with 5 X 5 quad
ruling allow for a graph of no more than 35 squares wide and 40 squares
tall.
3. ASSIGN VALUES TO AXES WHICH
INCLUDE THE RANGE LIMITS
Assign values to the coordinates which meet the
following requirements:
a. They include the limits
determined in step 1.
b. They make an adequately
large graph as large as the available space will accommodate.
c. They do not exceed the
space available on the page.
Determine the value to assign to each
square:
Divide the range value by the number of squares
available along the given axis. Round up so that the first
significant figure of the result equals a multiple of ten or decimal
fraction of 1, 2, 5 or 10 units per square. (I.e., 0.0207/square
would be rounded up to 0.05/square). Memorize the numbers 1, 2, 5, or 10.
Other values will make plotting the data difficult (and will cost you
points when graded). The quantity zero should often be the space
most to the left and/or bottom.
4. CONSTRUCT AXES, MARK WITH
REGULAR VALUES
Draw lines for the X-axis below and the Y-axis to
the left of the selected open area on the graph paper. Label each
axis. Mark off the selected regular values with a small line
corresponding to units/square selected in step 2: often every 5 or 10
squares. (Do not mark every square.) Label each mark with
its corresponding value. Be
certain to maintain linearity: all spaces must have equal value.
5. ENTER DATA POINTS
For the first point, locate the appropriate value
along the X axis and then follow that line up until the appropriate
value of Y is reached. Double check that you have not shifted
from the desired location, and make a small dot at the point.
Draw a small circle around the point, making it easier to see, but
preserving the integrity of the point. Repeat until all data have
been entered.
Use squares to indicate a second data set, triangles
the third, etc.
6. CONNECT THE CIRCLES
If the function you are graphing is linear,
carefully connect the circles
by lining a ruler up with the points and drawing a line between
them. (Do not violate the
interior of the circles so that the value of the point will
remain clear.)
Alternatively, if the function is non linear, you
may either connect the circles or approximate the curve plots with a
"best fit" curve.
7. TITLE THE GRAPH AND AXES
Create a title which is meaningful and explicitly reflects the
value of the experimental data you have graphed. Place it
in CAPITAL LETTERS as the title of the page. Below the title,
indicate from where the original data came with a cross
reference. Be certain that the axes are correctly and precisely
labeled. Label any significant break points or phases in the
curve, briefly indicate their meaning, if known.