topic Help with Shewhart Control Chart in SAS Studio

Help with Shewhart Control Chart

annaabimbola — Thu, 08 Jul 2021 23:13:42 GMT

I'm want to create an XSchart

this is the code I used but the chart was split into 5 instead of 1. The dates in my data are 09/01/2020, 10/01/2020, 11/01/2020, and so on. Do I need to include something that will make just 1 chart?

title "Length of Stay";
symbol v=dot;

proc shewhart data=work.nowsbaseline_sorted;
	xschart neonatald*measureperiodid;
run;

Re: Help with Shewhart Control Chart

PaigeMiller — Wed, 07 Jul 2021 20:35:22 GMT

Try something like this

xschart neonatald*measureperiodid/haxis='01SEP2020'd to '01JUL2021'd by month;

You might also want to consider using a shorter format on the x-axis, for example assigning format YYMM5. to the x-axis variable, or using the TURNHLABELS option in PROC SHEWHART.

Re: Help with Shewhart Control Chart

annaabimbola — Wed, 07 Jul 2021 20:35:03 GMT

I tried that code but I got the same result.

Re: Help with Shewhart Control Chart

PaigeMiller — Wed, 07 Jul 2021 20:37:57 GMT

Hello, @annaabimbola

From now on, when code isn't working, SHOW US THE LOG (and from now on, do not wait until we request to see the log). We need to see the ENTIRE log for your PROC SHEWHART, all of it, 100%, every character of the log for PROC SHEWHART. Do not pick and choose parts of the PROC SHEWHART log to show us.

IMPORTANT INSTRUCTIONS: copy the log as text, then paste it into the window that appears when you click on the </> icon. DO NOT SKIP THIS STEP.

Re: Help with Shewhart Control Chart

annaabimbola — Wed, 07 Jul 2021 20:50:45 GMT

1          OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
 72         
 73         
 74         title "Length of Stay";
 75         symbol v=dot;
 76         
 77         proc shewhart data=work.nowsbaseline_sorted;
 78         xschart neonatald*measureperiodid/haxis='01SEP2020'd to'01JUL2021'd by month;
 79         *xschart neonatald*measureperiodid;
 80         run;
 
 NOTE: Processing beginning for XSCHART statement number 1.
 ERROR: HAXIS values must be uniformly spaced.
 WARNING: Default axis scaling will be used.
 NOTE: Three-sigma limits are assumed.
 NOTE: TYPE=ESTIMATE is assumed for the process mean and standard deviation used to compute the control limits.
 NOTE: Since the format MMDDYY is associated with the subgroup variable MeasurePeriodID, it is assumed that the natural interval 
       between subgroup positions is one DAY.
 NOTE: The REPEAT option is assumed when a MMDDYY format is used with a subgroup variable.
 NOTE: There were 146 observations read from the data set WORK.NOWSBASELINE_SORTED.
 NOTE: PROCEDURE SHEWHART used (Total process time):
       real time           1.67 seconds
       user cpu time       0.79 seconds
       system cpu time     0.06 seconds
       memory              40867.59k
       OS Memory           71280.00k
       Timestamp           07/07/2021 08:46:54 PM
       Step Count                        44  Switch Count  0
       Page Faults                       0
       Page Reclaims                     13755
       Page Swaps                        0
       Voluntary Context Switches        1675
       Involuntary Context Switches      3
       Block Input Operations            0
       Block Output Operations           5176
       
 
 81         
 82         OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
 94

Re: Help with Shewhart Control Chart

PaigeMiller — Wed, 07 Jul 2021 21:35:03 GMT

ERROR: HAXIS values must be uniformly spaced.

Hmmm ... must be I mis-remembered that you can use months in PROC SHEWHART on the x-axis. It is kind of picky about things like that.

You can assign an integer index to each of your dates.

So, assign 01SEP2020 the index of 1, 01OCT2020 the index of 2, and so on. Then use this index as your horizontal axis variable. Also create a variable YEAR which contains 2020 and 2021, and a variable month which is 1 through 12 for each time period. Then

xschart neonatald*index (year month);

You can see examples here: https://documentation.sas.com/doc/en/qcug/15.2/qcug_shewhart_sect473.htm

Re: Help with Shewhart Control Chart

annaabimbola — Wed, 07 Jul 2021 21:02:05 GMT

Thank you, I'll try that.