Provides the expected values of the ordered data under normality. These scores can be used to produce normal probability plots and various tests.
Syntax
NSCORES(number)
For number, specify the column number.
Example
To determine if the expected values of a column of data (C1) are from a normal distribution, enter the expression NSCORE(C1) and store the results in C2.
Loosely speaking, -1.55 is the smallest value you would expect to get if you
took a sample of size 10 from a standard normal (i.e., the expected value of the
first order statistic), and -0.66 is the second smallest value you would expect
to get (i.e., the expected value of the second order statistic), and so
on.
C1
C2
0.1
−1.54664
0.2
−0.65542
1.1
−0.12258
1.5
0.12258
3.8
0.37546
5.4
0.65542
6.9
1.54664
6.6
1.00049
0.3
−0.51042
0.3
−0.51042
Minitab does not calculate the expected values of the order statistics exactly, but
uses percentage points as an approximation. Thus, if there are n data values,
Minitab uses the following equation for the ith smallest data value:
In the equation, i is the rank of the observation and F
-1(x) is the inverse cumulative distribution function of the
standard normal distribution.
Observations that are equal have the same normal score. This score uses the average
rank of the equal observations.
