Introduction to Graphing

1. Title

2. The independent variable (w/ axis title)

3. The dependent variable  (w/ axis title)

4. The scales for each variable

5. A legend or key (if necessary)

A graph contains five major parts: (5 MGP: “5 Major Graph Parts”)

Graphing is an important procedure used by scientists to display the data that is collected during a controlled experiment. Graphs must be constructed correctly to accurately portray the data collected for analysis. Many times the wrong construction of a graph inaccurately portrays data or skews perception about a data set, so being able to accurately create and analyze a graph is an extremely important scientific skill. 

Graphing

Introduction to Graphing

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.

TITLE

A graph Contains...

The INDEPENDENT VARIABLE: is the variable that can be controlled or manipulated by the experimenter. It usually includes time (dates, minutes, hours, etc.), depth (feet, meters), and temperature (Celsius). This variable is placed on the X axis (horizontal axis). [MIX - manipulated, independent, X]

 INDEPENDENT VARIABLE

A graph Contains...

The DEPENDENT VARIABLE: is the variable that is directly affected by the independent variable or responds to changes in 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 Y or vertical axis. [DRY - dependent, responding, Y]

 DEPENDENT VARIABLE

A graph Contains...

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 consistent scale must be utilized to include all the data points. The scale should 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 scale should start with 0 and climb or decrease 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. Scales must be consistent, with number intervals spaced evenly!

SCALES

A graph Contains...

The LEGEND/KEY: is the meaning of the symbols used in a graph or map. This could include shapes or colors to help the reader determine what the lines or bars on a graph mean. Always use a legend/key if more than one data set is represented on the same graph.

LEGEND/KEY

A graph Contains...

​allow us to compare groups or categories

​​Bar Graphs

​allow us to show trends over time or in sequential order

​​Line Graphs

​Types of Graphs

is anything that can be counted or measured; it refers to numerical data

Quantitative Data

is descriptive, referring to things that can be observed but not measured

Qualitative Data

Data

Open Ended

What are the 5 major graph parts that should always be included when creating a graph?

Open Ended

Write TWO statements to summarize 2 other things you learned about graphs from this page:

Mean

​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 

Median

​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).

Mode

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

Multiple Choice

What does the term independent variable mean?

• The independent variable is the result of the experiment
• Independent variable is not relevant in experiments
• The term independent variable refers to the factor that is manipulated

• Independent variable is always constant

Multiple Choice

What does the term dependent variable mean?

• The dependent variable is the cause of the experiment.
• The dependent variable is always constant.
• The dependent variable is the outcome being measured in an experiment.
• The dependent variable is not affected by the independent variable.

Match

Match the following:

• Mean

• Median

• Mode

The average

The middle value

The most frequent value

• The average

• The middle value

• The most frequent value