RELATIONPLOT Statement |
You use the RELATIONPLOT statement to create life-stress relation plots. A life-stress relation plot is a graphical tool for the analysis of data from accelerated life tests. The plot is a display of the relationship between life and stress, such as temperature or voltage. You can also use the RELATIONPLOT statement to display a probability plot alongside the relation plot. See Figure 14.9 for an example of a relation plot.
You can specify the keyword RPLOT as an alias for RELATIONPLOT. You can use any number of RELATIONPLOT statements after a PROC RELIABILITY statement. You can specify an optional label to distinguish between multiple RELATIONPLOT statements in the output.
See the section Analysis of Accelerated Life Test Data for an example that uses the RELATIONPLOT statement.
To create a life-stress relation plot, you must specify one variable. If your data are right censored, you must specify a censor-variable and, in parentheses, the values of the censor-variable that correspond to censored data values. You must specify one group-variable to represent the values of stress. The group-variable must be a numeric variable.
The RELATIONPLOT statement plots the uncensored values of your data given by variable versus the values of the group-variable. You can optionally display a boxplot of the values of the data. You can also plot percentiles of the distribution fitted to the data. The RELATIONPLOT statement produces the same tabular output as the PROBPLOT statement, and all the analysis options are the same as for the PROBPLOT statement.
The elements of the RELATIONPLOT statement are described as follows.
represents the data for which a plot is to be produced. The variable must be a numeric variable in the input data set.
indicates which observations in the input data set are right censored. You specify the values of censor-variable that represent censored observations by placing those values in parentheses after the variable name. If your data are not right censored, then you omit the specification of censor-variable; otherwise, censor-variable must be a numeric variable in the input data set.
is another method of specifying the data for which a life-stress plot is to be produced. You can use this syntax in a situation where uncensored, interval-censored, left-censored, and right-censored values occur in the same set of data. Table 14.27 shows how you use this syntax to specify different types of censoring by using combinations of missing and nonmissing values. See the section Lognormal Analysis with Arbitrary Censoring for an example that uses this syntax to create a probability plot.
is a group variable. The group-variable must be a numeric variable in the input data set.
control the features of the relation plot. All options are specified after the slash (/) in the RELATIONPLOT statement. The "Summary of Options" section, which follows, lists all options by function.
The only type of relation plot currently available for interval data is the type in which percentiles of the fitted distribution are plotted at each stress level.
Option |
Option Description |
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CONFIDENCE=number |
Specifies the confidence coefficient for all confidence intervals. The number must be between 0 and 1. The default value is 0.95. |
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CONVERGE=number |
Specifies the convergence criterion for maximum likelihood fit. See the section Maximum Likelihood Estimation for details. |
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CONVH=number |
Specifies the convergence criterion for the relative Hessian convergence criterion. See the section Maximum Likelihood Estimation for details. |
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CORRB |
Requests the parameter correlation matrix. |
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COVB |
Requests the parameter covariance matrix. |
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FITTYPE | FIT= fit-specification |
Specifies the method of estimating distribution parameters. The available fit-specifications and their meanings are shown in the following table. |
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ITPRINT |
Requests the iteration history for the maximum likelihood fit. |
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LRCL |
Requests likelihood ratio confidence intervals for distribution parameters. |
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LRCLPER |
Requests likelihood ratio confidence intervals for distribution percentiles. |
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LOCATION=number <LINIT> |
Specifies a fixed or initial value of the location parameter. |
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MAXIT=number |
Specifies the maximum number of iterations allowed for a maximum likelihood fit. |
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NOPCTILES |
Suppresses computation of percentiles. |
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PCTLIST=number-list |
Specifies a list of percentages for which to compute percentile estimates. The number-list must be a list of numbers separated by blanks or commas. Each number in the list must be between 0 and 100. If this option is not specified, percentiles are computed for a standard list of percentages. |
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PPOS=plotting-position |
Specifies the plotting-position type used to compute nonparametric estimates of the probability distribution function. See the section Probability Plotting for details. The plotting position types available are shown in the following table. |
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PPOUT |
Requests a table of nonparametric cumulative probabilities in the printed output. |
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PSTABLE=number |
Specifies a stable parameterization. The number must be between zero and one. See the section Stable Parameters for further information. |
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RELATION=transformation-keyword |
Specifies the type of relationship between independent (stress) and dependent (lifetime) variables. The transformation specified is applied to the independent (stress) variable in the model. This determines the horizontal scale used in the relation plot. transformation-keyword can be any of the transformations listed in the following table. See Table 14.61 for definitions of the transformations. |
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READOUT |
Specifies the data has the readout structure. |
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SCALE=number <SCINIT> |
Specifies a fixed or initial value of scale parameter. |
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SHAPE=number <SHINIT> |
Specifies a fixed or initial value of shape parameter. |
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SINGULAR=number |
Specifies the singularity criterion for matrix inversion. |
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Requests that survival function be computed for values in number-list. See the section Reliability Function for details. |
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THRESHOLD=number |
Specifies a fixed threshold parameter. See Table 14.51 for the distributions with a threshold parameter. |
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variable=number-list |
Enables creation of plots of percentiles from a regression model when two independent variables are used in a MODEL statement effect-list. The FIT=REGRESSION option must be used with this option. Percentile plots are created for each value of the independent variable in the number-list. number-list is a list of numeric values separated by blanks or commas, or in the form of a list to <by >. |
Table 14.42 lists plot layout options that are available when you use traditional graphics.
Option |
Option Description |
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CENSYMBOL=symbol | (symbol-list) |
Specifies symbols for censored values. The symbol is one of the symbol names (plus, star, square, diamond, triangle, hash, paw, point, dot, circle) or a letter (A–Z). If you are creating overlaid plots for groups of data, you can specify different symbols for the groups with a list of symbols or letters, separated by blanks, enclosed in parentheses. If no CENSYMBOL option is specified, the symbol used for censored values is the same as for failures. |
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HOFFSET=value |
Specifies an offset for horizontal axis. |
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INBORDER |
Requests a border around plots. |
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LBOXES=number |
Specifies a line style for boxplots. |
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LFIT=linetype | (linetype-list)) |
Specifies line styles for fit lines and confidence curves in a probability plot. The linetype-list is a list of numbers from 1 to 46 representing different linetypes; the numbers can be separated by blanks or commas or can be a list in the form to <by >. |
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LPLOTFIT=linetype | (linetype-list)) |
Specifies line styles for percentile lines. linetype-list is a list of numbers that represent different linetypes; the numbers can be separated by blanks or commas or can be a list in the form to <by >. |
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NOCENPLOT |
Suppresses plotting of censored data points. |
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NOCONF |
Suppresses plotting of percentile confidence curves. |
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NOFIT |
Suppresses plotting of fit line and percentile confidence curves. |
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NOFRAME |
Suppresses the frame around the plotting area. |
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NOPPLEGEND |
Suppresses the legend for overlaid probability plots. |
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NOPPOS |
Suppresses plotting of symbols for failures in a probability plot. |
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NORPLEGEND |
Suppresses the legend for the relation plot. |
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PINTERVALS=interval-type |
Specifies the type of parametric pointwise confidence interval displayed in a probability plot. The available types of intervals are listed in the following table. The default type is PROBABILITY, pointwise confidence intervals on cumulative failure probability. |
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PLOTDATA <DATA | MEDIANS | BOXES> |
Requests that the data be plotted on the relationplot and specifies the representation of the data populations to be plotted. |
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PLOTFIT <number-list> |
Specifies that percentiles of the fitted distribution be plotted on the relation plot. The optional number-list is a list of percentiles (between 0 and 100); if not specified, the 50th percentile (median) is plotted. |
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PPLEGEND = legend-statement-name |
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| NONE |
Identifies a LEGENDn statement to specify legend for overlaid probability plots. |
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PPLOT |
Places a probability plot on the same page as the relation plot. |
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RCENSYMBOL=symbol | (symbol-list) |
Specifies symbols that represent right-censored and left-censored observations in a relation plot. The symbol is one of the symbol names (plus, star, square, diamond, triangle, hash, paw, point, dot, circle) or a letter (A–Z). |
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RPLEGEND = legend-statement-name |
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| NONE |
Identifies a LEGENDn statement to specify legend for the relation plot. |
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SHOWMULTIPLES |
Displays the count for multiple overlaying symbols. |
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TURNVLABELS |
Vertically strings out characters in labels for vertical axis. |
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VOFFSET=value |
Specifies length of offset at upper end of vertical axis. |
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WFIT=linetype |
Specifies line width for fit line and confidence curves. |
Table 14.43 lists plot layout options that are available when you use ODS graphics.
Option |
Option Description |
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NOCENPLOT |
Suppresses plotting of censored data points. |
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NOCONF |
Suppresses plotting of percentile confidence curves. |
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NOFIT |
Suppresses plotting of fit line and percentile confidence curves. |
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NOPPOS |
Suppresses plotting of symbols for failures in a probability plot. |
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PINTERVALS=interval-type |
Specifies the type of parametric pointwise confidence interval displayed in a probability plot. The available types of intervals are listed in the following table. The default type is PROBABILITY, pointwise confidence intervals on cumulative failure probability. |
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PLOTDATA |
Requests that the data be plotted on the relationplot. |
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PLOTFIT <number-list> |
Specifies that percentiles of the fitted distribution be plotted on the relation plot. The optional number-list is a list of percentiles (between 0 and 100); if not specified, the 50th percentile (median) is plotted. |
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PPLOT |
Places a probability plot on the same page as the relation plot. |
Table 14.44 lists reference line options that are available when you use traditional graphics.
Option |
Option Description |
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HREF <(INTERSECT)>=value-list |
Requests reference lines perpendicular to horizontal axis. If (INTERSECT) is specified, a second reference line perpendicular to the vertical axis is drawn that intersects the fit line at the same point as the horizontal axis reference line. If a horizontal axis reference line label is specified, the intersecting vertical axis reference line is labeled with the vertical axis value. |
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HREFLABELS=(’label1’ ...’labeln’) |
Specifies labels for HREF= lines. |
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HREFLABPOS=n |
Specifies the vertical position of labels for HREF= lines. The valid values for n and the corresponding label placements are shown in the following table:
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LHREF=linetype |
Specifies a line style for HREF= lines. |
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LSREF=linetype |
Specifies a line style for SREF= lines. |
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LVREF=linetype |
Specifies a line style for VREF= lines. |
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SREF=value-list |
Specifies reference lines perpendicular to horizontal stress axis. |
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SREFLABELS=(’label1’ ...’labeln’) |
Specifies labels for SREF= lines |
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SREFLABPOS=n |
Specifies horizontal position of labels for SREF= lines. The valid values for n and the corresponding label placements are shown in the following table:
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VREF <(INTERSECT)>=value-list |
Requests reference lines perpendicular to vertical axis. If (INTERSECT) is specified, a second reference line perpendicular to the horizontal axis is drawn that intersects the fit line at the same point as the vertical axis reference line. If a vertical axis reference line label is specified, the intersecting horizontal axis reference line is labeled with the horizontal axis value. |
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VREFLABELS=(’label1’ ...’labeln’) |
Specifies labels for VREF= lines. |
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VREFLABPOS=n |
Specifies the horizontal position of labels for VREF= lines. The valid values for n and the corresponding label placements are shown in the following table:
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Table 14.45 lists reference line options that are available when you use ODS graphics.
Option |
Option Description |
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PREF <(INTERSECT)>=value-list |
Requests reference lines perpendicular to probability axis, if a probability plot is specified with the PPLOT option. If (INTERSECT) is specified, a second reference line perpendicular to the vertical axis is drawn that intersects the fit line at the same point as the horizontal axis reference line. If a horizontal axis reference line label is specified, the intersecting vertical axis reference line is labeled with the vertical axis value. |
PREFLABELS=(’label1’ ...’labeln’) |
Specifies labels for PREF= lines. |
SREF=value-list |
Specifies reference lines perpendicular to horizontal stress axis. |
SREFLABELS=(’label1’ ...’labeln’) |
Specifies labels for SREF= lines. |
LREF <(INTERSECT)>=value-list |
Requests reference lines perpendicular to vertical (lifetime) axis. If (INTERSECT) is specified, a second reference line perpendicular to the horizontal axis is drawn that intersects the fit line at the same point as the vertical axis reference line. If a vertical axis reference line label is specified, the intersecting horizontal axis reference line is labeled with the horizontal axis value. |
LREFLABELS=(’label1’ ...’labeln’) |
Specifies labels for LREF= lines. |
Table 14.46 lists options that control the appearance of the text when you use traditional graphics. These options are not available if ODS Graphics is enabled.
Option |
Option Description |
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FONT=font |
Specifies a software font for text. |
HEIGHT=value |
Specifies the height of text used outside framed areas. |
INFONT=font |
Specifies a software font for text inside framed areas. |
INHEIGHT=value |
Specifies the height of text inside framed areas. |
Table 14.47 lists options that control the appearance of the axes when you use traditional graphics.
Option |
Option Description |
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LAXIS=value1 TO value2<BY value3> |
Specifies tick mark values for the lifetime axis. value1, value2, and value3 must be numeric, and value1 must be less than value2. The lower tick mark is value1. Tick marks are drawn at increments of value3. The last tick mark is the greatest value that does not exceed value2. If value3 is omitted, a value of 1 is used. This method of specification of tick marks is not valid for logarithmic axes. Examples of LAXIS= lists are laxis = -1 to 10 laxis = 0 to 200 by 10 |
LGRID=number |
Specifies a line style for all grid lines. The number is between 1 and 46 and specifies a linestyle for grids. |
LIFELOWER | LLOWER=number |
Specifies the lower limit on the lifetime axis scale. The LLOWER option specifies number as the lower lifetime axis tick mark. The tick interval and the upper lifetime axis limit are determined automatically. This option has no effect if the LAXIS option is used. |
LIFEUPPER | LUPPER=number |
Specifies the upper limit on the lifetime axis scale. The LUPPER option specifies number as the upper lifetime axis tick mark. The tick interval and the lower lifetime axis limit are determined automatically. This option has no effect if the LAXIS option is used. |
MPGRID |
Adds a minor grid for the probability axis. |
MINORLOGGRID |
Adds a minor grid for log axes. |
NOGRID |
Suppresses grid lines. |
NOLLABEL |
Suppresses the label for the lifetime axis. |
NOLTICK |
Suppresses tick marks and tick mark labels for lifetime or analysis variable axis. |
NOPLABEL |
Suppresses the label for the probability axis. |
NOPTICK |
Suppresses tick marks and tick mark labels for probability axis. |
NOSLABEL |
Suppresses the label for the stress axis. |
NOSTICK |
Suppresses tick marks and tick mark labels for stress axis. |
NSTRESSTICK=number |
Specifies the number of tick intervals for stress axis for relation plot. |
NTICK=number |
Specifies the number of tick intervals for the lifetime axis. This option has no effect if the LAXIS option is used. |
PCTLOWER | PLOWER=number |
Specifies the lower limit on the probability axis scale. |
PCTUPPER | PUPPER=number |
Specifies the upper limit on the probability axis scale. |
STRESSLOWER | SLOWER=number |
Specifies the lower limit on the stress axis scale. |
STRESSUPPER | SUPPER=number |
Specifies the upper limit on the stress axis scale. |
PAXISLABEL=‘string’ |
Specifies a label for the probability axis. |
WAXIS=n |
Specifies the line thickness for axes and frame. |
Table 14.48 lists options that control the appearance of the axes when you use ODS Graphics.
Option |
Option Description |
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LIFELOWER | LLOWER=number |
Specifies the lower limit on the lifetime axis scale. The LLOWER option specifies number as the lower lifetime axis tick mark. The tick interval and the upper lifetime axis limit are determined automatically. This option has no effect if the LAXIS option is used. |
LIFEUPPER | LUPPER=number |
Specifies the upper limit on the lifetime axis scale. The LUPPER option specifies number as the upper lifetime axis tick mark. The tick interval and the lower lifetime axis limit are determined automatically. This option has no effect if the LAXIS option is used. |
NOGRID |
Suppresses grid lines. |
PCTLOWER | PLOWER=number |
Specifies lower the limit on the probability axis scale. |
PCTUPPER | PUPPER=number |
Specifies upper the limit on the probability axis scale. |
STRESSLOWER | SLOWER=number |
Specifies the lower limit on the stress axis scale. |
STRESSUPPER | SUPPER=number |
Specifies the upper limit on the stress axis scale. |
PAXISLABEL=‘string’ |
Specifies a label for the probability axis. |
Table 14.49 lists options that control the use of a graphics catalog to store graphs if you use traditional graphics. These options are not available if ODS Graphics is enabled.
Option |
Option Description |
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DESCRIPTION=‘string’ |
Description for graphics catalog member |
NAME=‘string’ |
Name for plot in graphics catalog |
Table 14.50 lists options that control colors and patterns used in the graph when you use traditional graphics. These options are not available if ODS Graphics is enabled.
Option |
Option Description |
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CAXIS=color |
Color for axis |
CBOXES=color |
Color for box frame for boxplots |
CBOXFILL=color |
Color for filling boxes for boxplots |
CCENSOR=color |
Color for filling censor plot area |
CENCOLOR=color |
Color for censor symbol |
CFIT=color | (color-list) |
color for fit lines and confidence curves in a probability plot |
CFRAME=color |
Color for frame |
CGRID=color |
Color for grid lines |
CHREF=color |
Color for HREF= lines |
CPLOTFIT=color | (color-list) |
colors for percentile lines |
CSREF=color |
Color for SREF= lines |
CTEXT=color |
Color for text |
CVREF=color |
Color for VREF= lines |
RCENCOLOR=color | (color-list) |
Colors for the symbols representing uncensored, right-censored, and left-censored observations in a relation plot |