Notes: Graphing

Purpose of graphing 1.Allows us to compare data easily 2.Creates a “picture” of the data that shows us tendencies or trends 3.Allows us to predict outcomes 4.Enables us to prove/disprove a hypothesis

Essentials of a Graph 1.Title (generic: y vs. x) 2.Labels for each axis 3.Units for each axis 4.Proper scale 5.Key (if more than one line)

Determine proper scale Step #1: Determine if zero is an appropriate starting point for data If your first data point is at 55 and your last is at 72, zero is not a good starting point. 55 is more appropriate to start at.

Determine proper scale Step #2: Determine range of data ( biggest value – smallest value) Ex: temperature data for y-axis starts at 25 o C and goes up to 100 o C. The range is 75 o C

Determine proper scale Step #3: Count how many spaces for the axis are available on the graph paper (x and y axis)

Determine proper scale Step #4: determine value of each space on the graph: Range / # spaces on axis 75 o C / 100 space =.75 o C /line This value is a starting point

Determine proper scale Step #5: round up to next “good” number:.001,.002,.0025,.005,.01,.02, ,.1,.2,.25,.5, 1, 2, 2.5, 5, 10, 20, 25, etc. Ex:.75 o C /line = 1 o C Scale is 1 o C or each space is 1 o C

Use the data to answer #1-3: 1.3, 40, 13, 2.5, 5.8, 52.9, 61, 32.7, 18, 52, 52.3, Determine the scale for a graph with 100 spaces on the axis? 2.50 spaces? 3.70 spaces?

Use the data to answer #1-3: 43.3, 20.3, 32.9, 34.1, 21.5, 28.4, 31.3, 31.5, Determine the scale for a graph with 100 spaces on the axis? 2.40 spaces? 3.30 spaces?

Use the data to answer #1-3: 45, 43, 87, 23, 46, 76, 56, 77, 87, 76, 23, 87, 55, 66, 73, 19, 25, 62, 71, 83, 38, 25, 29 1.Determine the scale for a graph with 100 spaces on the axis? 2.30 spaces? 3.40 spaces?