
I PLOTName:
An I plot is used in two ways:
For both applications, the resulting plot is similar in appearance. Namely, a target value which typically appears as an X, a vertical bar with small horizontal bars at the extremes (hence the name "I plot"). The I plot has five components (characters and lines) which can be individually controlled. These components are:
For the default I plot, the I PLOT command can be preceded by the following two commands:
LINES I PLOT With these commands, the first three lines are set to blank and lines four and five are set blank. The second character is set to "X", characters one and three are set to "", and characters four and five are set to blank. After the I plot is formed, the analyst should redefine plot characters and lines via the usual CHARACTERS and LINES commands. As mentioned above, the I plot can use location statistics other than the median. Specifically, you can use the MEAN I PLOT, MIDMEAN I PLOT, MIDRANGE I PLOT, TRIMMED MEAN I PLOT, and BIWEIGHT I PLOT to specify the mean, midmean, midrange, trimmed mean, and biweight location, respectively. This plot is also useful for displaying confidence intervals as well as other types of intervals. The following are currently supported:
where <stat> is MEDIAN, MEAN, MIDMEAN, MIDRANGE, BIWEIGHT, or TRIMMED MEAN; <y> is the response (= dependent) variable; <x> is the horizontal axis (= independent) variable; and where the <SUBSET/EXCEPT/FOR qualification> is optional. For this syntax, the extreme values will be the minimum and maximum values. If <stat> is omitted, the location statistic will be the median.
where <stat> is one of: MEAN CONFIDENCE LIMIT TRIMMED MEAN CONFIDENCE LIMIT MEDIAN CONFIDENCE LIMIT QUANTILE CONFIDENCE LIMIT BIWEIGHT CONFIDENCE LIMIT STANDARD DEVIATION CONFIDENCE LIMIT NORMAL TOLERANCE LIMIT NORMAL PREDICTION LIMIT AGRESTI COULL LIMIT ONE STANDARD ERROR TWO STANDARD ERROR ONE STANDARD DEVIATION TWO STANDARD DEVIATIONS <y> is the response (= dependent) variable; <x> is the horizontal axis (= independent) variable; and where the <SUBSET/EXCEPT/FOR qualification> is optional. For this syntax, the extreme values will be the lower and upper bounds of the appropriate limits.
<SUBSET/EXCEPT/FOR qualification> where <stat> is one of: MEDIAN I MEAN I MIDMEAN I MIDRANGE I BIWEIGHT I TRIMMED MEAN I MEAN CONFIDENCE LIMIT TRIMMED MEAN CONFIDENCE LIMIT MEDIAN CONFIDENCE LIMIT QUANTILE CONFIDENCE LIMIT BIWEIGHT CONFIDENCE LIMIT STANDARD DEVIATION CONFIDENCE LIMIT NORMAL TOLERANCE LIMIT NORMAL PREDICTION LIMIT ONE STANDARD ERROR TWO STANDARD ERROR ONE STANDARD DEVIATION TWO STANDARD DEVIATION <y1> ... <yk> is a list of up to k response variables; and where the <SUBSET/EXCEPT/FOR qualification> is optional. This syntax is useful when the data for each group is stored in separate response variables. Up to 30 response variables may be specified. Note that the syntax
is supported. This is equivalent to
<SUBSET/EXCEPT/FOR qualification> where <stat> is one of the variants listed for Syntax 3; <y> is the response variable; <x1> ... <xk> is a list of up to k groupid variables; and where the <SUBSET/EXCEPT/FOR qualification> is optional. This syntax performs a crosstabulation of <x1> ... <xk> and generates an i plot (on the same graph) for each unique combination of crosstabulated values. For example, if X1 has 3 levels and X2 has 2 levels, there will be a total of 6 i plots generated. Up to six groupid variables can be specified. Note that the syntax REPLICATED I PLOT Y X1 TO X4 is supported. This is equivalent to REPLICATED I PLOT Y X1 X2 X3 X4 In this syntax, all i plots are drawn with the sampe plot attributes. As an example of how the xcoordinates are determined, assume we have 3 levels for X1 and 2 levels for X2. The xcoordinates will be
<SUBSET/EXCEPT/FOR qualification> where <stat> is one of the variants listed for Syntax 3; <y> is the response variable; <x1> is the first groupid variable; <x2> is the second groupid variable; and where the <SUBSET/EXCEPT/FOR qualification> is optional. This syntax is similar to syntax 4. However, it has the following distinctions:
Program 2 demonstrates the difference between Syntax 4 and Syntax 5.
I PLOT Y X SUBSET X > 2 ONE STANDARD ERROR PLOT Y X MEAN CONFIDENCE LIMIT PLOT Y X
To specify the alpha level for the confidence limit cases, enter the command (0.05 will be used if this command is not given)
For the QUANTILE CONFIDENCE LIMIT case, specify the desired quantile with the command (0.50 will be used if this command is not given)
For the TRIMMED MEAN CONFIDENCE LIMIT case, specify the trimming parameters with the commands (0.25 and 0.75 will be used if these commands are not given)
LET P2 = <value>
2011/02: Support for MULTIPLE and REPLICATION options 2013/10: Support for MEAN, MIDMEAN, MIDRANGE I plots 2013/10: Support for various confidence interval cases (Syntax 2) 2013/10: Support for special 3 variable case (Syntax 5) . Step 1: Read the data . skip 25 read gear.dat y x . . Step 2: Basic iplot . title case asis title offset 2 label case asis character case asis line i plot character blank circle blank blank blank character fill off on character hw 0.5 0.375 all xlimits 1 10 major xtic mark number 10 minor xtic mark number 0 x1tic mark offset 0.5 0.5 title automatic . multiplot corner coordinates 5 5 95 95 multiplot scale factor 2 multiplot 2 2 i plot y x mean i plot y x midrange i plot y x midmean i plot y x end of multiplot . multiplot 2 2 one standard error plot y x two standard error plot y x mean confidence limit plot y x median confidence limit plot y x end of multiplot . multiplot 2 2 mean confidence limit plot y x median confidence limit plot y x biweight confidence limit plot y x trimmed mean confidence limit plot y x end of multiplotProgram 2: . Step 1: Read the data . . y = voltage drop . x1 = elapsed days (1, 8, 15, 29, 43, 57, 71, 107) . x2 = type of connector . 1 = brass . 2 = steel . 3 = innovative skip 25 read clark0.dat y days x2 let days = 8 subset days = 9 let days = 15 subset days = 16 let days = 29 subset days = 30 let days = 43 subset days = 44 let days = 57 subset days = 58 let days = 71 subset days = 72 let days = 107 subset days = 108 let x1 = coded days let nx1 = unique x1 let nx2 = unique x2 let ntot = nx1*nx2 . . Step 2: I Plot with standard replication option . title case asis title offset 2 label case asis character case asis line i plot character blank circle blank blank blank character fill off on character hw 0.5 0.375 all . y1label Voltage Drop x3label Elapsed Days/Connector Type xlimits 1 ntot major xtic mark number ntot minor xtic mark number 0 x1tic mark offset 0.5 0.5 x1tic mark label format alpha x1tic mark label content 1 8 15 29 43 57 71 107 1 8 15 29 43 57 71 107 ... 1 8 15 29 43 57 71 107 x1tic mark label size 1.6 title automatic replicated i plot y x2 x1 . justification center let xcoor = (nx1/2) + 0.5 let ycoor = 10 moveds xcoor ycoor text Brass let xcoor = xcoor + nx1 moveds xcoor ycoor text Steel let xcoor = xcoor + nx1 moveds xcoor ycoor text Innovative . . Step 3: I Plot with alternative replication option . line i plot bl bl bl so so bl bl bl so so bl bl bl so so character bl circ bl bl bl bl circ bl bl bl bl circ bl bl bl character fill on all character hw 0.5 0.375 all character color blue blue blue blue blue red red red red red ... green green green green green line color blue blue blue blue blue red red red red red ... green green green green green . x1label Elapsed Days/Connector Type x3label xlimits 1 nx1 major xtic mark number nx1 minor xtic mark number 0 x1tic mark offset 0.5 0.5 x1tic mark label format alpha x1tic mark label content 1 8 15 29 43 57 71 107 title automatic i plot y x1 x2  
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Date created: 11/05/2013 