Thanks for you answer. I want to make sure my calculation is correct. The 
details of protein prophet result is -

*Minimum probability**Sensitivity**Error rate*0.001.00000.89600.101.0000
0.23900.201.00000.23900.300.96700.17800.400.94100.14600.500.90700.11700.60
0.86300.08900.700.80800.06400.800.73900.04200.900.62900.02100.950.52100.0090
0.960.50100.00700.970.47400.00600.980.41300.00300.990.36900.00101.000.0860
0.0000


Based on this result, what is 
probability cutoff that gives me 1% FDR? 

Thanks 

Sandeep





On Friday, March 15, 2013 11:01:24 AM UTC-5, kshitiz wrote:
>
> Sorry I probably was not clear enough. Number of unique peptides for a 
> protein are actually number of PSMs, so hypothetically if a protein was 
> identified based on one peptide that was fragmented 10 times and 8 out of 
> those 10 ms/ms spectra result in peptide spectrum match , then number of 
> unique peptides will read 8 however you have identified only one peptide. 
>
> I hope someone on the forum can correct me if I am wrong.
>
> Additionally, you said that you filter at p > 0.9, this is not very 
> informative and not the best way of filtering. Instead you should filter at 
> a p value that controls for less than 1% FDR.
>
> cheers
>
>
> On Fri, Mar 15, 2013 at 3:05 PM, Sandeep <[email protected]<javascript:>
> > wrote:
>
>> Hello, 
>>
>>   Sorry, I think I did not understand your answer. My concern was- why I 
>> have more number of unique peptides as compared to TOTAL number of peptides 
>> in my data after protein prophet grouping and filtering my data to contain 
>> only groups with probability more than 0.9. 
>>
>> Thanks
>>
>> Sandeep
>>
>>
>>
>>
>> On Friday, March 15, 2013 3:41:11 AM UTC-5, kshitiz wrote:
>>>
>>> Hi,
>>> I think the number given under number of unique peptides is actually 
>>> number of unique PSMs used for the identity of that protein. If you want 
>>> actual number of unique peptides then you will have to pull the data into 
>>> an SQL based server and then query it to to count distinct peptides for 
>>> each protein.
>>>
>>> cheers.
>>>
>>>
>>> On Thu, Mar 14, 2013 at 10:00 PM, Sandeep <[email protected]> wrote:
>>>
>>>> Hi, 
>>>>
>>>> I have recently started using peptide/proteinprophet. I noticed that in 
>>>> my data, there are several protein groups for which the number of unique 
>>>> peptidees is more than the number of total peptides (mostly the total 
>>>> number of peptides is 0). Is this data reliable? How to explain this. 
>>>> Thanks in advance for any answers. 
>>>>
>>>> Sandeep
>>>>
>>>>
>>>>
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>>>
>>>
>>> -- 
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>>>
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>
> -- 
> Kshitiz Tyagi
>
>  

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