SRP 10 –How to do “Chi square”
Chi-square directions
Go to GraphPad http://www.graphpad.com/quickcalcs/chisquared1.cfm
The categories are the color chart values, 1 - 10. You must group them together so that no group will have a
zero in the other columns.
The “expected” column is the control group. For example: enter the number of trials in the control group
that were a 1, 2, or 3. If any of the values is zero, you must regroup the color values to eliminate zeroes.
The “observed” column is the experimental group. For example: enter the number of trials in the control
group that were a 1, 2, or 3. If any of the values is zero, you must regroup the color values to eliminate
zeroes.
If you have more than one experimental group, you must do the calculations separately for each group,
always comparing back to the control “expected” column.
on a scale
of 1-10
* Make sure the total of Observed & the total of Expected is equal.
* Do not use 0.
Click on
The next page will look something like this. Record these numbers in the chart below.
The following is the table that will go on your board and in the Results section of your paper.
Table 1: Statistics
Control (e)
Experimental (o)
median
frequency
distribution
1-3
4-6
7-9
10
df
Chi-square
table value
P value
14
frequency distribution - these will be the same as the data you entered above.
df = degrees of freedom and = (# rows -1) x (# columns -1) [ (4 - 1 = 3) x (2-1)] = 3
Table value - look up in the table below. (It will be 7.81 if there are 3 degrees of freedom.)
For the P value, write “< 0.05” or “> 0.05”