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If there is a close agreement between the observed and expected
frequencies, x
2
will be small. If the agreement is poor, x
2
will be large.
The following keystrokes calculate the x
2
statistic:
1. Press CLEAR .
2. Key in the first O
i
value and press .
3. Key in the first E
i
value and press 0 0
.
4. Repeat steps 2 and 3 for all data pairs. The x
2
value is displayed.
Example 1: A suspect die from a Las Vegas casino is brought to an
independent testing firm to determine its bias, if any. The die is tossed 120
times and the following results obtained.
The expected frequency = 120 throws / 6 sides, or E = 20 for each
number, 1 thru 6. (Since E is a constant in this example, there is no need
to store it in R
0
each time.)
Number 1 2 3 4 5 6
Observed Frequency 25 17 15 23 24 16
Keystrokes Display
CLEAR
25
20 0
0
1.25
17 20
0
1.70
x
2
O
i
E
i
–()
E
i
---------------------
i 1=
n
∑
=