
5. Select the corresponding t eld.
6.
Enter an expression and press . The independent variable must be X, and the expression
must not contain any unknown variables. For example, 1.5 * cos(x) + 0.3 * sin(x). Note that in this app,
variables must be entered in uppercase.
Computed statistics
When you tap , three sets of statistics become available. By default, the statistics involving both the
independent and dependent columns are shown. Tap to see the statistics involving just the
independent column or to display the statistics derived from the dependent column. Tap
to return to the default view. The tables below describe the statistics displayed in each view.
The statistics computed when you tap are as follows:
Statistic Denition
n The number of data points.
r Correlation coeicient of the independent and dependent data columns, based only on
the linear t (regardless of the t type chosen). Returns a value between –1 and 1, where
1 and –1 indicate best ts.
R
2
The coeicient of determination, that is, the square of the correlation coeicient. The
value of this statistics is dependent on the Fit type chosen. A measure of 1 indicates a
perfect t.
sCOV Sample covariance of independent and dependent data columns.
σCOV Population covariance of independent and dependent data columns.
ΣXY Sum of all the individual products of x and y.
The statistics displayed when you tap are as follows:
Statistic Denition
ẋ Mean of x- (independent) values.
ΣX Sum of x-values.
ΣX
2
Sum of x
2
-values.
sX The sample standard deviation of the independent column.
σX The population standard deviation of the independent column.
serrX The standard error of the independent column.
ssX Sum of the squared deviations of X.
The statistics displayed when you tap are as follows:
Computed statistics 255
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