Line Graphs, Columns, Pie Charts and X-Y, Oh My!

An overview of graph types and when to use them

Line Graphs

• When comparing changes over time

• When comparing changes amongst two or more variables over the same amount of time

• Examples include growth, rates, etc…

Line Graphs

Assumptions in Excel

• That all time comparisons are on equal interval. So there needs to be an equal amount of time between reporting results.

• If not, you can see standardized time intervals that shouldn’t be represented…

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Use x-y scatter plots for non-uniform time intervals

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Colums Graphs

• Used in a comparison of data

• Can show differences in such factors that are usually not time dependent

• Should include pertinent comparisons (i.e., results of a survey, data totals, etc…

Column Graphs

Pie Charts

• Useful to breakdown a cluster of data that equals a total sum (into portions or percentages)

• This graph is a good way to show proportions

• Examples include percentages of a total population that comprise certain species, etc…

Pie Charts

Pie Chart Examples

X-Y Scatter Plots• A direct comparison between two variables

(how one variable may affect another)

• These show a cause and effect relationship in a graphical format

• The more independent variable is on the x axis (controlled variable) with the experimental variable on the y axis

X-Y Scatter Plots

X-Y Scatter Plots

Error Bars• Error bars are important to account for the

range of error in a data set

• In column graphs, they could be denoted as 5% error, or Standard Deviation, or Standard Error

• We will cover this aspect more in depth, but I will show you how to use these on column graphs

Error Bars

What is missing from this column graph?

The error bars here represent a 5% error