1. Graphing 101

2. Draw and Identify the Axes

3. Remember DRY MIX R- Responding I- Independent Y- Y-axis X- X-axis
D- Dependent M-Manipulated
R- Responding I- Independent
Y- Y-axis X- X-axis

4. The title should contain both the independent and dependent variables.
Example: How Temperature Affects The Respiration Rate of Goldfish

5. Scale
min and max numbers used on each axis. (Does not have to begin at zero).
min and max numbers should be a little lower than lowest value and a little higher than the highest value
Chose a scale that will utilize most of the graph paper
This allows you to have a smaller range which emphasizes the comparisons/trends in the data.

6. The Best Scale
Graph #1
The Y-axis scale is from but the largest value is only 35.
Graph #2
The Y-axis scale is now from 0-40.
---2nd Graph does a better job emphasizing the comparisons between coins.

7. Steps to Find Scale
Find the range of the data for the Y Axis (67-32= 35)
Count number of lines/boxes on axes (20)
Divide the range number by the number of boxes (35÷20=1.75) round to 2 to make easier
Each box will be worth 2 degrees
Repeat for the X Axis (6÷20=0.33)
Each box is worth less than a day, box =1 day
Each third line should be labeled with the day

9. Intervals The interval is the amount between one value and the next
Look at your minimum and maximum values you set up for both the Y and X-axis.
Use appropriate interval for the scale you have chosen.
Highly recommended to use a common number for an interval such as 2, 5, 10, 25, 100, etc.

10. Intervals The interval for the Y-axis is 8
The X-axis does not have numerical data and does not need an interval.

11. Labels
Both axes need labels so we know exactly what the independent and dependent variables are.
The dependent variable must be specific and include the units used to measure the data (such as “number of drops”).
DV label
IV label

12. Labels
DV label
IV label

13. TAILS T.A.I.L.S. Scale Title Axis
Another handy acronym to help you remember everything you need to create your graphs…..
T.A.I.L.S.
Title
Axis
Interval
Labels
Scale

14. Bar Graphs vs Line Graphs

15. Bar Graphs Bar graphs are descriptive.
They compare groups of data such as amounts and categories.
They help us make generalizations and see differences in the data.

16. Line Graphs
Line graphs show a relationship between the two variables. They show how/if the IV affects the DV.
Many times, the IV plotted on the X-axis is time.
They are useful for showing trends in data and for making predictions.
Can be used to compare multiple sets of data, using different lines within the same graph

17. Example

18. Multiple Sets of Data
When graphing multiple data sets on the graph, use a distinctive color of pen, or style of line, for each data set.
Place an example of the color or line style off to the side of the graph (Key)
Label it with the name of the information being displayed. For example: Seedlings

20. Analyzing Data: Standard Deviation and Standard Error

21. Examine data points. Observe the pattern the data forms on the graph.
From the pattern the data makes on the graph, determine the type of relationship between the x and y variables.
Most times it will be best to use a smooth continuous line called a “best fit” line.
Draw your best fit line so that it goes a little past your last data point.

22. A measure of how spread out the data is from the mean
Standard Deviation:
A measure of how spread out the data is from the mean
Lower standard deviation:
Data is closer to the mean
Greater likelihood that the independent variable is causing the changes in the dependent variable
Higher standard deviation:
Data is more spread out from the mean
More likely factors, other than the independent variable, are influencing the dependent variable

23. Actual data sets aren’t always so pretty...

24. Measure of accuracy, if the true mean is known
Standard Error:
Indication of how well the mean of a sample (x) estimates the true mean of a population (μ)
Measure of accuracy, if the true mean is known
How close a measured value is to the TRUE value
Measure of precision, if true mean is not known
How close a measured value is to other measured values

25. How do we use Standard Error? Create bar graph mean on Y-axis
sample(s) on the X-axis
chemical 1 mean = 30 cm
chemical 2 mean = 50 cm

26. Add error bars!
± SE
Indicate in figure caption that error bars represent standard error (SE)

27. Analyze! Look for overlap of error lines:
If they overlap: The difference is not significant
If they don’t overlap: The difference may be significant

28.   Which is a valid statement?
Fish2Whale food caused the most fish growth
Fish2Whale food caused more fish growth than did Budget Fude  

29. Statements:
In all four regions, more males exhibited the trait measured than did females.
More males in region 3 exhibited the measured trait than did females  