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Module 1 – section 1
When do we use each type of graph?
You would use a line graph if you wanted to show what happens to data over time. For example: how to compare the amount of money spent on school supplies from 1990 to 2004. You can have a double line graph if you wanted to compare the amount of money spent on school supplies and clothes from 1990 to 2004.
You would use a bar graph when you want to compare how different areas items are affected by one type of data. For example: You can use a bar graph to compare the number of students that prefer different lunch choices: The lunch preference is the item affected by the data (the students choice). You can use a bar graph to compare the types of fuel used to heat people’s homes. Sometimes the data is expressed as a percent.
Percent means out of 100. If 45% of the people used oil to heat their homes, it means that less than half the homes were heated by oil. So if there are 120,000 homes in Nassau County, less than 60,000 were heated by oil. It does not mean that 45 homes were heated by oil!
Both bar and line graphs contain:
A horizontal axis: the x-axis – these are the lines that run width-wise
And a vertical axis: the y-axis – these are the lines that run up and down
All graphs must include:
Labels for the x-axis and the y-axis
Data Labels: What does the graph represent?
Scale: What does each interval represent? An interval is the space between two lines (on either axis). The intervals on a graph must be the same. For example the scale can be counting by 5’s, 10’s, 100’s etc.