[R] How to make t.test handle "NA" and "essentially constant values" ?

[Richard Pearson]

Do you mean to deal with the situation where you're doing many t-tests 
in a loop? If so there was a post very recently on this list about this:

https://stat.ethz.ch/pipermail/r-help/2008-February/153254.html

Richard.


Ng Stanley wrote:
> Thanks. Someone please help to make t.test go through all the data and not
> to be disrupted by the two problems.
>
> On 2/12/08, Petr PIKAL <petr.pikal at precheza.cz> wrote:
>   
>> Hi
>>
>> r-help-bounces at r-project.org napsal dne 12.02.2008 09:09:23:
>>
>>     
>>> Hi,
>>>
>>> First problem:
>>>       
>>>> test <- matrix(c(1,1,2,1), 2,2)
>>>> apply(test, 1, function(x) { t.test(x) $p.value })
>>>>         
>>> Error in t.test.default(x) : data are essentially constant
>>>       
>> make your data not constant
>>
>>     
>>> Second problem:
>>>       
>>>> test <- matrix(c(1,0,NA,1), 2,2)
>>>> apply(test, 1, function(x) { t.test(x) $p.value })
>>>>         
>>> Error in t.test.default(x) : not enough 'x' observations
>>>       
>> increase number of observations
>>
>>
>>     
>>> How to make t-test ignores this errors ?
>>>       
>> Well, the procedure is complaining that you do not give it correct data.
>> You shall be gratefull for a great software which prevent you from making
>> silly things as try to compute t.test when data have zero variantion or
>> number of observations is 1.
>>
>> Regards
>> Petr
>>
>>     
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>>>
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>
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>
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