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The SGPANEL Procedure

LOESS Statement

Creates a fitted loess curve.


Syntax

LOESS X= numeric-variable Y= numeric-variable </ option(s)>;

option(s) can be one or more options from the following categories:

Required Arguments

X= numeric-variable

specifies the variable for the x axis.

Y= numeric-variable

specifies the variable for the y axis.

Options

ALPHA= numeric-value

specifies the confidence level for the confidence limits. Specify a number between 0.00 (100% confidence) and 1.00 (0% confidence).

Note:   This option has no effect if you do not specify the CLM option.  [cautionend]

Default: .05
CLM <= "text-string">

creates confidence limits for a mean predicted value for each observation. The optional text string overrides the default legend label for the confidence limit.

CLMATTRS = style-element

specifies the appearance of the confidence limits by using an ODS style element.

Default: The default appearance of the confidence limits is specified by the GraphConfidence style element in the current style.
CLMTRANSPARENCY= numeric-value

specifies the degree of transparency for the confidence limits. Specify a value from 0.0 (completely opaque) to 1.0 (completely transparent).

Note:   This option has no effect if you do not specify the CLM option.  [cautionend]

Default: 0.0
CURVELABEL <="text-string">

adds a label for the loess curve. You can also specify the label text. If you do not specify a label, the label from the Y variable is used.

CURVELABELPOS= MIN | MAX | START | END

specifies the location of the curve label. Specify one of the following values:

MIN

places the curve label at the minimum value for the X axis.

MAX

places the curve label at the maximum value for the X axis.

START

places the curve label at the first point on the curve.

END

places the curve label at the last point on the curve.

Default: END
DATALABEL <= variable>

displays a label for each data point. If you specify a variable, then the values of that variable are used for the data labels. If you do not specify a variable, then the values of the Y variable are used for the data labels.

Interaction: This option has no effect if you also specify the NOMARKERS option.
DEGREE= 1 | 2

specifies the degree of the local polynomials to use for each local regression. 1 specifies a linear fit and 2 specifies a quadratic fit.

Default: 1
GROUP= variable

specifies a classification variable to divide the values into groups. A separate plot is created for each unique value of the classification variable.

Interaction: If you specify the GROUP= option in multiple fit plot statements, then the first GROUP= variable is used for all of the fit plots that specify GROUP=.
INTERPOLATION= CUBIC | LINEAR

specifies the degree of the interpolating polynomials that are used for blending local polynomial fits at the kd tree vertices.

Default: CUBIC
LEGENDLABEL= "text-string"

specifies a label that identifies the fit line in the legend. By default, the label "Loess" is used, along with the value of the SMOOTH= option if specified.

LINEATTRS= style-element <(options)> | (options)

specifies the appearance of the fit curve. You can specify the appearance by using a style element or by using suboptions. If you specify a style element, you can additionally specify suboptions to override specific appearance attributes.

options can be one or more of the following:

COLOR= color

specifies the color of the line. For more information about specifying colors, see SAS/GRAPH Colors and Images in the SAS/GRAPH: Reference, Second Edition.

Default: For ungrouped data, the default color is specified by the ContrastColor attribute of the GraphFit style element in the current style.

For grouped data, the default color is specified by the ContrastColor attribute of the GraphData1 ... GraphDatan style elements in the current style.
PATTERN= line-pattern

specifies the line pattern for the line. You can reference SAS patterns by number or by name. See Line Patterns for a list of line patterns.

Default: For ungrouped data, the default line pattern is specified by the LineStyle attribute of the GraphFit style element in the current style.

For grouped data, the default line pattern is specified by the LineStyle attribute of the GraphData1 ... GraphDatan style elements in the current style.
THICKNESS= n <units>

specifies the thickness of the line. You can also specify the unit of measure. The default unit is pixels. See Units of Measurement for a list of the measurement units that are supported.

Default: For ungrouped data, the default line thickness is specified by the LineThickness attribute of the GraphFit style element in the current style.

For grouped data, the default line thickness is specified by the LineThickness attribute of the GraphData1 ... GraphDatan style elements in the current style.
MARKERATTRS= style-element <(options)> | (options)

specifies the appearance of the markers in the plot. You can specify the appearance by using a style element or by using suboptions. If you specify a style element, you can additionally specify suboptions to override specific appearance attributes.

options can be one or more of the following:

COLOR= color

specifies the color of the markers. For more information about specifying colors, see SAS/GRAPH Colors and Images in the SAS/GRAPH: Reference, Second Edition.

Default: For ungrouped data, the default color is specified by the ContrastColor attribute of the GraphDataDefault style element in the current style.

For grouped data, the default color is specified by the ContrastColor attribute of the GraphData1 ... GraphDatan style elements in the current style.
SIZE= n <units >

specifies the size of the markers. You can also specify the unit of measurement. The default unit is pixels. See Units of Measurement for a list of the measurement units that are supported.

Default: The default marker size is specified by the MarkerSize attribute of the GraphDataDefault style element in the current style.
SYMBOL= symbol-name

specifies the symbol for the markers. See Marker Symbols for a list of valid marker symbols.

Default: For ungrouped data, the default marker symbol is specified by the MarkerSymbol attribute of the GraphDataDefault style element in the current style.

For grouped data, the default marker symbol is specified by the MarkerSymbol attribute of the GraphData1 ... GraphDatan style elements in the current style.
MAXPOINTS= n

specifies the maximum number of predicted points for the loess fit and the corresponding limits.

Default: 201
NAME= "text-string"

specifies a name for the plot. You can use the name to refer to this plot in other statements.

NOLEGCLM

hides the legend entry for the mean value confidence limits.

NOLEGFIT

hides the legend entry for the fit line.

NOMARKERS

removes the scatter markers from the plot.

REWEIGHT= n

specifies the number of iterative reweighting steps to apply to the data.

Note:   This option has no affect if you do not specify the WEIGHT option.  [cautionend]

Default: 0
SMOOTH= numeric-value

specifies a smoothing parameter value. If you do not specify this option, a smoothing value is determined automatically.

WEIGHT= numeric-variable

specifies that each observation is weighted by a factor of w for computational purposes, where w is the value of the numeric variable. w can be any numeric value. If w is 0, negative or missing, then that observation is excluded from the analysis.

Details

For the SMOOTH= option, the smoothing parameter value must be greater than the minimum value that is determined by the following equation:

[equation]

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