GRAPHING NOTES

Graphs are helpful because they create pictures of the data collected. They can show trends, patterns or relationships that may exist within the data.

Line Graphs

● Line graphs are usually used to show time series data -that is how one or more variables change over a continuous period of time

● Line graphs can also be appropriate for displaying data that are measured over other continuous variables such as temperature or pH ranges.

● Line graphs are particularly useful for identifying patterns and trends in the data

LOCATE YOUR Y AXIS!THIS IS WHERE YOU WILL PLACE THE INDEPENDENT VARIABLE.

Y Axis

LOCATE YOUR X AXIS!THIS IS WHERE YOU WILL PLACE THEDEPENDENT VARIABLE.

X Axis

REMEMBER DRY MIX TO HELP WITH VARIABLES!

Same variable, different name!

Same variable, different name!

TITLE YOUR GRAPH!

Here’s a few simple tips:

● Steal the name for the graph from up above the data table!

OR

● Substitute the actual names for the independent and dependent variables into the following statement:

● The effect of independent variable on the dependent variable.

DETERMINING RANGE AND SCALE !

● Decide on an appropriate scale for each axis.

● Choose a scale that lets you make the graph as large as possible for your paper and data.

● Scale is determined by your highest & lowestvalues found on each side of the data table.

● Each axis will have it’s own scale.

How to Determine Scale

• For the x axis, it will be 2002 minus 1995. That is a difference of 7.

• For the y axis, it will be 2600 minus 2000.That is a difference of 600.

Xaxis

Yaxis

How to Determine Intervals

• An interval is the amount of space between one number on a graph to the next number or one type of data to the next type of data.

• Each interval on an axis should be of equal value and evenly spaced.

• The interval is decided by using your range.

• It is always best to try to go with the smallest interval possible as this will spread the data out over the greatest area.

● It is not necessary to start your scale at zero.

● Do not use breaks in your graph.

Minnesota Wolf Population

2000

2600

2700

Years

Est

ima

ted

Pop

ulat

ion

95 96 97 98 99 00 01 02

• Graphs not only have the data, but they show changes in the data.

• When interpreting graphs you are basically making an observation as to how the dependent variable on the x axis is responding to the independent variable on the y axis.

• This allows you to see if there is some type of pattern or trend in the data.

Interpreting Graphs

POPULATION GRAPHSTHEY EACH TELL A DIFFERENT STORY!

1. The population remained the same over time.2. The population suddenly started increasing very quickly! 3. The population steadily increased over time.

# 1 # 2 # 3

BAR GRAPHS

• They are used to display and compare the number, frequency or other measures for different categories or groups of things.

• Since the x-axis (the horizontal axis) represents the different categories it has no scale.

• The y-axis (the vertical axis) does have a scale and this indicates the units of measurement.

• There are various ways in which bar graphs can be constructed and this makes them very flexible.

Examples of Bar Graphs

HORIZONTAL OR VERTICAL ?

● It doesn’t make any difference! ● The graph still says the same thing!