[R] offlist comment Re: KS Test question (2)

[Siri Bjoner]

Just my $0.02...

There have been a number of postings and questions on the list in the  
last couple of weeks (that is, there seems to be a larger percentage  
of such mail than usual...).

Maybe a "happy monthly reminder" could be sent out with the posting  
guide? And maybe there could be something like "Write a sentence on  
where you've searched for answers" so that responses such as the one  
below may be avoided.

I don't post a lot, as I prefer replying offlist and don't really have  
any specific questions, but it seems that there is an increasing  
amount of posts where newbie hasn't read the posting guides or  
someone's homework needs to be done (forgive me if I'm mistaken, but I  
thought this list didn't do kids' homework?).

Anyhows, not meant to annoy, just a couple of thoughts.

Siri.

Siterer "Ralf B" <ralf.bierig at gmail.com>:

> This is unbelievable. Now people like yourself start doing background
> searches on one and accusing one of not being professional plus
> posting cheeky R code. The reason why I submitted the questions I have
> submitted was that these answers did not satisfy my particular problem
> (or perhaps I mistakenly thought so). The point here is that the forum
> should be a forum where one should be allowed to ask questions without
> first studying the history of the the entire forum in fear that
> someone might have asked it before. I was hoping that I could find
> clearer answers then what I was able to read. I do know how to search
> in Google. But I am not an expert in statistics, as you already found
> in your background check. If I would be fluent in stastitsics and R
> and if past answers would have exactly satisfied my problem I would
> not post here and I certainly would not have occupied your expensive
> attention.
>
>
>
>
>
> On Wed, Aug 4, 2010 at 6:16 PM, David Winsemius  
> <dwinsemius at comcast.net> wrote:
>>
>> On Aug 4, 2010, at 5:49 PM, Ralf B wrote:
>>
>>> Hi R Users,
>>>
>>> I have two vectors, x and y, of equal length representing two types of
>>> data from two studies. I would like to test if they are similar enough
>>> to use them interchangeably. No assumptions about distributions can be
>>> made (initial tests clearly show that they are not normal).
>>> Here some result:
>>>
>>> Two-sample Kolmogorov-Smirnov test
>>>
>>> data:  x and y
>>> D = 0.1091, p-value < 2.2e-16
>>> alternative hypothesis: two-sided
>>>
>>> Warning message:
>>> In ks.test(x[1:nx], y[1:nx], exact = FALSE) :
>>>  cannot compute correct p-values with ties
>>>
>>> Here some questions:
>>>
>>> a) What does the error message means and what does it imply?
>>> b) The data is very noisy and the initial result shows that there is
>>> no relation between x and y. Is there a way to calculate and effect
>>> size?
>>> c) Can the p-value be used, when running tests over a large amount of
>>> different data sets, as a metric for ranking similarity between x and
>>> y data sets?
>>
>> There has been quite a bit of discussion on this list over the years about
>> why KS test is not good in this situation. If I read the results of a search
>> on your name correctly, you are in a department of Information Sciences. I
>> would have thought that the first reaction of someone in that field would be
>> do do a search on a question. Why are you filling up the archives with
>> questions that have been repeatedly asked and  answered?
>>
>> Do you need help in this area?
>>
>> rhelpSearch <- function(string,
>>                  restrict = c("Rhelp10", "Rhelp08", "Rhelp02", "functions"
>> ),
>>                  matchesPerPage = 100, ...)
>>         RSiteSearch(string=string,  restrict = restrict,  matchesPerPage =
>> matchesPerPage, ...)
>>
>>
>> rhelpSearch("KS.test ties p-value")
>>
>>>
>>> Best
>>> R.
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>
>> David Winsemius, MD
>> West Hartford, CT
>>
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>