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If
necess
drp,
ffi
3ffim
3ffi
4ilm
ffi
5ilru
ffi
6ffi
ffi
use
EJ
or
[Yl to
display the moving
average equation.
Displays menu of
variables.
H=3
,
Bg
Stores
number
of
points.
Calculates average
for
]'IHUG=4
, ??B
,
86
months
l,
2, and
3.
Calculates average
for
l,lHUG=3
,976,6?
months 2, 3, and
4.
Calculates average
for
]'IHVG=S,
535
.
67
months 3, 4, and
5.
Calculates average
for
l,lHUG=3, 63
6
,67
months 4, 5, and
6.
\-,
\-,
\-,
\-,
\./
\./
\-/
\-,
\-,
\-,
\-,
\-,
\-
Chi-squared
1x2l
Statistics
The Chi-squared statistic is a measure
of
the goodness
of
fit
between
data and an assumed distribution.*
It
is used to test whether a set of
observed frequencies
differs from a
set
of
expected frequencies
suffi-
ciently to reject the hypothesis under which the expected frequencies
were obtained.
In
other words, you are testing whether
discrepancies
between
the observed frequencies
(O;) and
the
expected
frequencies
(Er)
are
significant,
or whether they may
reasonably
be attributed
to
chance.
The equation
is:
x2:
i
(o,:E,)'
i:l
tr;
If
there
is
close agreement
between the observed and expected fre-
quencies,
xz is small;
if
the
agreement
is
poor, x2
is
large.
*
The statistic can be
assumed
to
be
x2
distributed
with
n
1
degrees
of
freedom
if.
n
or
some
of
the
E;
values are
large.
\-/
\.,
\-,
9: Additional
Eramples
183
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