1. One of the first steps in data analysis is to create graphical displays of the data. Visual displays can make it easy to see patterns and can clarify how two variables affect each other.
AP Biology Quantitative Skills Manual

2. Line Graphs
Used when data on both scales of the graph (the x and y axes) are continuous.
The dots indicate measurements that were actually made.

3. Basic Traits of A Good Graph
1. A Good Title
A good title is one that tells exactly what information the author is trying to present with the graph.
Relation Between Study Time and Score on a Biology Exam in 2011
Try and avoid using “vs”
Study Time vs. Score on a Biology Exam in 2011
AP® Biology Investigative Labs: An Inquiry-Based Approach

4. Basic Traits of A Good Graph
Axes should be consistently numbered.
Axes should contain labels, including units.
AP® Biology Investigative Labs: An Inquiry-Based Approach

5. Basic Traits of A Good Graph
A frame should be put around the outside of the graph.
AP® Biology Investigative Labs: An Inquiry-Based Approach

6. Basic Traits of A Good Graph
Small marks, called index marks, can be drawn in.
AP® Biology Investigative Labs: An Inquiry-Based Approach

7. Basic Traits of A Good Graph
The independent variable is always shown on the x axis.
The dependent variable is always shown on the y axis.
Dependent
Variable
AP® Biology Investigative Labs: An Inquiry-Based Approach
Independent
Variable

8. Basic Traits of A Good Graph
The line should not be extended to the origin if the data do not start there.
9. Use a dashed line if extrapolating (extending) beyond your experimental
AP® Biology Investigative Labs: An Inquiry-Based Approach

9. Bar Graphs
Used to visually compare two samples of categorical or count data.
Are also used to visually compare the calculated means with error bars of normal data .
AP Biology Quantitative Skills Manual

10. Sample standard error bars (also known as the sample error of the sample mean) are the notations at the top of each shaded bar that shows the sample standard error (SE).
AP Biology Quantitative Skills Manual