1
Review of Chapter 2
s
Range
: one measure of variability
b
Not used to calculate the variance
s
Calculating mean
: (aka “the average”) the
fulcrum around which all the other scores
balance
Review of Chapter 2
s
Calculating the variance:
s
1. find the mean
s
2. subtract the mean from each score
b
This is the deviation score
s
3. Square the deviation score
s
4. Add the squared deviation scores
b
This is the Sums of Squares
s
5. Divide the Sums of Squares by n1
b
“n” = the number of participants
s
**The range is not needed for these calculations
Standard Deviation
s
*Not mentioned in Chapter 2*
s
Standard Deviation
: the square root of the
variance
s
If the mean
and standard deviation
of a normal
distribution
are known
b
it is possible to compute the percentile rank
associated with any given score.
b
In a normal distribution, about 68% of the scores are
within one standard deviation of the mean and about
95% of the scores are within two standards deviations
of the mean
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document2
Calculating Variance and the
Standard Deviation
Mean=5.6
5.6^2=31.36
05.6=5.6
0
5
4.4^2=19.36
105.6=4.4
10
4
3.4^2=11.56
95.6=3.4
9
3
.6^2=.36
55.6=.6
5
2
1.6^2=2.56
45.6=1.6
4
1
Squared Deviation
Deviation Score
Score
Participant
Calculating Variance and the
Standard Deviation
= 65.2
+ 31.36
19.36
11.56
.36
2.56
Sum of
Deviation
score
s
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '07
 TRCunningham
 Normal Distribution, Standard Deviation, Alfred Binet, deviation score

Click to edit the document details