Graphing Skill #1: What Type of Data do I Have?

The types of data that you have will tell you what type of graph will work best.  We will group them into 3 types (Yes in class we talked about 4 types but remember that 2 of them are often interchangeable, so we will count them as 1 group for determining which graph to use).

Types of Data

  Percent: Percent data means that it is part of a whole.  Don't be confused by its name.  Look at the data and see "does this add up to a whole of something?"  If it does then you have percent data.  A percent sign is not always percent data.  

Examples:

• If I look at how much time I spend doing different activities in a day, those are hours but add up to 1 whole day so it is percent data.
• I can write down student scores as percents, but they do not add up to a whole grade when looking at one test for 30 students, so not percent data.  

Categories: Data that is one or the other.  You can not get something that is in between.  This type is basically just putting things into groups.  Groups can be rearranged and put in different orders without messing up my data.

Examples:

• We survey students on what pets they have.  Some will have dogs, others will have cats.  When I arrange my groups I can put cats first or dogs first, so these are categories.
• Data is taken of the amount of rain each month.  Months have names but it would mess up the data to put February before January, they have an order so they are not categories.

Scales: Data that has a logical order and/or I can go back and find data that is halfway between points I already have.  These tend to be numbers, but anything with a logical order falls here.

Examples:

• We are looking at the amount of energy in colors of light.  It turns out that light colors are determined by wavelength and change color as the wavelength lengthens or shortens, they have a specific order they happen in so in this case color is a Scale.
• If I group people up and give each group a number, these group numbers are just titles so even though they are numbers there is no logical order that the groups have to go in, so in this case numbers are categories not a count, amount, or scale.

Identify the types of data that you have in the following situations: