From: Liaw, Andy <andy_liaw_at_merck.com>

Date: Sat 23 Apr 2005 - 01:47:34 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Apr 23 02:05:16 2005

Date: Sat 23 Apr 2005 - 01:47:34 EST

That looks just like how `outliers' are determined in boxplots. You can use
the output of boxplot.stats() to compute the limits.

[EDA purists would tell you that those shound be letter values (or `F' for fourths), not quartiles.]

**HTH,
**

Andy

> -----Original Message-----

*> From: r-help-bounces@stat.math.ethz.ch
**> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of
**> khobson@fd9ns01.okladot.state.ok.us
**> Sent: Friday, April 22, 2005 11:23 AM
**> To: r-help@stat.math.ethz.ch
**> Subject: [R] Hoaglin Outlier Method
**>
**>
**>
**>
**>
**>
**> I am a new user of R so please bear with me. I have reviewed
**> some R books,
**> FAQs and such but the volume of material is great. I am in
**> the process of
**> porting my current SAS and SVS Script code to Lotus Approach, R and
**> WordPerfect.
**>
**> My question is, can you help me determine the best R method
**> to implement
**> the Hoaglin Outlier Method? It is used in the Appendix A and
**> B of the fo
**> llowing link. http://trb.org/publications/nchrp/nchrp_w71.pdf
**>
**> The sample data from Appendix A for determining outliers in R:
**> T314Data <-
**> structure(list(Lab = as.integer(c(1:60)), X = c(4.89, 3.82, 2.57, 2.3,
**> 2.034, 2, 1.97, 1.85,
**> 1.85, 1.85, 1.84, 1.82, 1.82, 1.77, 1.76, 1.67, 1.66, 1.63, 1.62,
**> 1.62, 1.55, 1.54, 1.54, 1.53, 1.53, 1.44, 1.428, 1.42, 1.39,
**> 1.36, 1.35, 1.31, 1.28, 1.24, 1.24, 1.23, 1.22, 1.21, 1.19, 1.18,
**> 1.18, 1.18, 1.17, 1.16, 1.13, 1.13, 1.099, 1.09, 1.09, 1.08,
**> 1.07, 1.05, 0.98, 0.97, 0.84, 0.808, 0.69, 0.63, 0.6, 0.5), Y
**> = c(5.28,
**> 3.82, 2.41, 2.32, 2.211, 1.46, 2.24, 1.91, 1.78, 1.63, 1.81,
**> 1.92, 1.2, 1.67, 1.28, 1.59, 1.45, 2.06, 1.91, 1.19, 1.26, 1.79,
**> 1.39, 1.48, 0.72, 1.29, 1.517, 1.71, 1.12, 1.38, 0.93, 1.36,
**> 1.2, 1.23, 0.71, 1.29, 1.26, 1.48, 1.26, 1.33, 1.21, 1.04, 1.57,
**> 1.42, 1.08, 1.04, 1.33, 1.33, 1.2, 1.05, 1.24, 0.91, 0.99, 1.06,
**> 1.27, 0.702, 0.77, 0.58, 1, 0.38)), .Names = c("Lab", "X", "Y"
**> ), class = "data.frame", row.names = c("1", "2", "3", "4", "5",
**> "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16",
**> "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27",
**> "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38",
**> "39", "40", "41", "42", "43", "44", "45", "46", "47", "48", "49",
**> "50", "51", "52", "53", "54", "55", "56", "57", "58", "59", "60"
**> ))
**>
**> >From this point on, I could use your advise. There are several other
**> methods for determining outliers in R. I'd rather not
**> re-invent the wheel
**> or use a brute strength and force method if there is a better
**> way in R.
**>
**> Our usual method for determining outliers is a student's T
**> test as in ASTM
**> E 178 or when the standard deviation for a lab is 3 or more.
**> We normally
**> have 120 labs to evaluate for outliers similar what is shown
**> in T312Data.
**> On occasion, I have used the Wilk-Shapiro W statistic in SAS.
**> A point in
**> the right direction or an R code example would help greatly.
**> After I trim
**> the outliers, I will need to show which labs were eliminated but that
**> should be fairly trivial.
**>
**> The reference in Appendix A is:
**> Hoaglin, D. C., Iglewicz, B., Tukey, J. W., "Performance of
**> Some Resistant
**> Rules for Outlier Labeling," Journal
**> of the American Statistical Association, Vol. 81, No. 396
**> (Dec., 1986), pp.
**> 991-999.
**>
**> The ASTM E 178 reference is:
**> Shapiro, S. S., and Wilk, M. B., "An Analysis of Variance Test for
**> Non-Normality (Complete Samples)," Biometrika, BIOKA, Vol 52,
**> 1965, pp. 591-611.
**>
**> Kenneth Ray Hobson, P.E.
**> Oklahoma DOT - QA & IAS Manager
**> 200 N.E. 21st Street
**> Oklahoma City, OK 73105-3204
**> (405) 522-4985, (405) 522-0552 fax
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide!
**> http://www.R-project.org/posting-guide.html
**>
**>
*

>

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Apr 23 02:05:16 2005

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