Transcript Graphing Basics

Graphing Basics
Why graph?
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Graphing is an important procedure
used by scientists to display the data
that is collected during a controlled
experiment.
5 Major parts of a graph
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Title – depicts what the graph is about – concise
statement
Independent Variable – variable that can be
controlled by the experimenter. (place on the x axis)
Dependent Variable – variable the is directly
affected by the IV (place on the y axis)
Scales for each variable – includes all the data
points. Scales climb in intervals such as multiples of
2,5,10, 25,30,50,60 or 100
Legend – short descriptive narrative concerning the
graph – concise and placed under the graph.
Bar Graphs
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Bar graphs are an excellent way to
show results that are one time, that
aren't continuous - especially
samplings such as surveys,
inventories, etc
Bar Graph
Below is a typical survey asking
students about their favorite after
school activity. Notice that in this graph
each column is labeled - it is also
possible to label the category to the left
of the bar. In this case, the numbers for
each category are across the bottom of
the chart.
Favorite Student After School Activity
Activity
Number
Visit W/Friends
175
Talk on Phone
168
Play Sports
120
Earn Money
120
Use Computers
65
Histograms
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Plots of continuous data and are often used
to represent frequency distributions, where
the y-axis shows the number of times a
particular measurement or value was
obtained.
The data are numerical and continuous
(height, weight), so the bars touch.
The x-axis usually records the class interval.
The y-axis usuall records the number or
individuals in each class interval (frequency)
Histogram
Pie Graphs
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Pie graphs can be used instead of bar
graphs, generally in cases where there
are six or fewer categories involved.
A pie graph provides strong visual
impact of the relative proportions in
each category, particularly where one
of the categories is very dominant.
Pie Graph
Percent of Hours of a Day Spent on Activities
ACTIVITY
HOURS
PERCENT OF
DAY
Sleep
6
25
School
6
25
Job
4
17
Entertainment
4
17
Meals
2
8
Homework
2
8
Line Graphs
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Line graphs are used when one
variable (IV) affects another (DV).
Figure 2 Dependence of the rate of fluorogenic peptide
dephosphorylation on enzyme concentration
Positive correlation
between the increase in
% dephosphorylation
and the increase in
enzyme concentration.
Graphs
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Show the relationships and trends
between variables.
Visual image of the data using minimal
space.