Graphing SkillsLines, Bars and Pies

Types of Graphs Line (a lot of data, often involving time)

› Used when there may be a trend or pattern Age versus Height

Bar (counting)› Used for somewhat unrelated items

Number of Dog, Cats and Fish as pets Pie (if a total is involved)

› Used to show how one thing is part of a whole thing Percent of votes in an election (Part/Whole) * 100%

Bar Graph

Independent Variable› What the scientist picks› What the scientist can control

Type of droppers, I could have used a turkey baster or snot sucker

Dependant Variable› The result of the independent variable

The number of drops DEPENDED of which dropper we used

Scale› MUST be equal

EVERY line MUST mean something 2, 4, 5, 1.2 Doesn’t matter as long as you keep it the same

Can be altered ONCE using a ‘break’ across the axis The break is usually a diagonal equal sign or a heartbeat

(see examples above) ONLY used if there is a LARGE gap in ALL the data

› To Find your scale Figure out how much data you have then, count the amount of space you have and divide: Example: 39 drops of water was the most so go to

40 I have 11 lines to fit it on my graph 40 ÷ 11 = 3.64 If I go by 3.8 or 4 it will fit well

Line Graphs follow the same basic rules as bar graphs.

Can have multiple lines. Line doesn’t always have to start at zero.

Pie Graphs› Data is shown as a percent of a whole.

To Calculate Percent› Find the part you want› Divide it by the total› Take that answer and multiply it by 100

(part/whole) * 100 Calculation Example:

› 68 people voted› Marcia got 25 votes› Sam got 31 votes and› Ian got the rest