Introduction

Graphing is
an important procedure used by scientists to display the data that is
collected during a controlled experiment

Line graphs must be constructed
correctly to accurately portray the data collected

Many times the
wrong
construction of a graph detracts from the acceptance of an individual’s
hypothesis

A graph
contains five major parts:
a.
Title b. The independent variable c. The
dependent variable d. The
scales for each variable e. A
legend

The title:
depicts what the graph is about. By reading the title, the reader should get
an idea about the graph. It should be a concise statement placed above the
graph.

The
Independent Variable: is the variable that can be controlled by the
experimenter. It usually includes time (dates, minutes, hours), depth (feet,
meters), temperature (Celsius). This variable is placed on the X axis
(horizontal axis).

The
Dependent Variable: is the variable that is directly affected by the
independent variable. It is the result of what happens because of the
independent variable. Example: How many oxygen bubbles are produced by a
plant located five meters below the surface of the water? The oxygen bubbles
are dependent on the depth of the water. This variable is placed on the
Yaxis or vertical axis.

The Scales
for each Variable: In constructing a graph one needs to know where to
plot the points representing the data. In order to do this a scale must be
employed to include all the data points. This must also take up a
conservative amount of space. It is not suggested to have a run on scale
making the graph too hard to manage. The scales should start with
0
and climb based on intervals such as: multiples of 2, 5, 10, 20, 25, 50, or
100. The scale of numbers will be dictated by your data values.

The Legend:
is a short descriptive narrative concerning the graph's data. It should be
short and concise and placed under the graph.

The Mean
for a group of variables: To determine the mean for a group of
variables, divide the sum of the variables by the total number of variables
to get an average.

The median
for a group of variables: To determine median or “middle” for an
even number of values, put the values in ascending order and take the
average of the two middle values.
e.g. 2,
3, 4, 5, 9, 10 Add
4+5 (2 middle values) and divide by 2 to get 4.5

The mode
for a group of variables: The mode for a group of values is the number
that occurs most frequently.
e.g. 2, 5,
8, 2, 6,
11 The
number 2 is the mode because it occurred most often (twice)
Procedure 1:
Using the following data, answer the questions below and
then construct a line graph.
Depth
in meters

Number
of Bubbles / minute Plant A

Number
of Bubbles / minute Plant B

2

29

21

5

36

27

10

45

40

16

32

50

25

20

34

30

10

20

1. What is the dependent variable and why?
2. What is the independent variable and why?
3. What title would you give the graph? .
4. What are the mean, median, and mode of
all 3 columns of data?
a). Depth :
Mean____________Median__________Mode________
b). Bubble Plant A.:
Mean ____________Median_________Mode________
c). Bubbles Plant B:
Mean ____________Median_________Mode________
Graph Title:
_________________________________________________________
Legend:
______________________________________________________________
Procedure 2:
Diabetes is a disease affecting the insulin producing
glands of the pancreas. If there is not enough insulin being produced by these
cells, the amount of glucose in the blood will remain high. A blood glucose
level above 140 for an extended period of time is not considered normal. This
disease, if not brought under control, can lead to severe complications and even
death.
Answer the following questions concerning
the data below and then graph it.
Time
After Eating hours

Glucose
mg /dL of Blood Person A

Glucose
mg /dL of Blood Person B

0.5

170

180

1

155

195

1.5

140

230

2

135

245

2.5

140

235

3

135

225

4

130

200

1. What is the
dependent variable and why?
2. What is the independent variable and why?
3. What title would you give the graph?
4. Which, if any, of the above individuals
(A or B) has diabetes?
5. What data do you have to support your
hypothesis?
6. If the time period were extended to 6
hours, what would the expected blood glucose level for Person B?
Title:
________________________________________________________________
Legend:
______________________________________________________________
Summary:
1. What conclusions can be determined from the data in
graph 1?
2. What conclusions can be determined from
the data in graph 2?
3. Can the data in each of these graphs be
used to construct other types of graphs?
4. If so, what other graph types can be
constructed?
