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T
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h
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e
‘
‘
S
S
t
t
a
a
t
t
-
-
T
T
w
w
o
o
’
’
g
g
r
r
o
o
u
u
p
p
o
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f
f
f
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u
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n
n
c
c
t
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i
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o
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s
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PREDY(x-val)
This function predicts the y value for a pair of columns set up as bivariate
data in the Statistics aplet. This is discussed in more detail in the section
covering the Statistics aplet, but a brief summary will be given here.
It assumes that:
(i) the bivariate data is entered into a pair of columns (eg. C1 and C2, with C1
containing the independent data and C2 the dependent data),
and (ii) that these two columns have been specified in the SYMB view to be paired
bivariate data,
and (iii) that this data set has been graphed in the PLOT view and that the FIT screen
key has been used to plot the line of best fit for the pair of columns,
If these conditions are satisfied then the
function PREDY(3.5) will produce a predicted
y (dependent) value for the x (indep.) value of
35⋅ .
Calculator Tip
The line of best fit used in the function PREDY is whichever
one was last plotted. It is up to you to ensure that this is in
fact the one you want used! It is far easier and more
reliable to use the facilities provided in the PLOT view (see
page 140) to calculate PREDY values.
PREDX(y-val)
The PREDX function simply reverses the line of best fit. For example, the
equation
ˆ
0 8199 1 1662YX=⋅ +⋅
earlier would use
( 1.1662)
ˆ
0.8199
Y
X
=
to predict
the X values.
Note: See page 146 for important information on this function.
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