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

[Ralf B]

Hi David,

I would like to apologize for what I wrote earlier. It was late and I
was frustrated. Please give me time to adapt to the formal structures
of the forum.

Best,
Ralf

On Thu, Aug 5, 2010 at 7:32 AM, David Winsemius <dwinsemius at comcast.net> wrote:
>
> On Aug 5, 2010, at 4:10 AM, Ralf B wrote:
>
>> This is unbelievable. Now people like yourself start doing background
>> searches on one and accusing one of not being professional
>
> Your words, not mine.
>
>> plus posting cheeky R code.
>
> It appeared that you were having problems and did not have an efficient
> strategy for searching the archives, so I shared with you code that I
> developed and have put in my .Rprofile setup file. I do no see where that is
> "posting cheeky R code". I saw it as trying to be constructive. Using it
> would only be part of the recommended actions to take before posting
>
>
>> 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.
>
> If you read the Posting Guide I think you will find precisely the opposite
> expectation explicitly presented. Using my "cheeky code" would only be part
> of the recommended actions to take before posting if you follow the
> recommendations of the "Do your homework before posting:" section. This list
> was not set up to be a chat room or a tutoring center for general questions
> in statistics.
>
> While you are reading the Posting Guide, please note that it expresses this
> advice regarding posting messages that were sent privately:
>
> "Take care when you quote other people's comments to respect their rights,
> e.g., as summarized here. In particular
>
>        • Private messages should never be quoted without permission,  "
>
>
>> 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.
>
>
> --
> David Winsemius, MD
> West Hartford, CT
>
>