How you caluculate sensitivity and selectivity of Blast?
Answers were Sorted based on User's Feedback
Answer / rishu
Suppose the Blast search returned 100 hits. Of these, 17
were false positives and we knew that there were 165
sequences in
the database which should have returned a hit with our
sequence.
To calculate the sensitivity and selectivity, we must
determine the number of true positives (ntp), the number of
false
positives (nfp) and the number of false negatives (nfn). We
are told that the number of false positives was 17, hence
the
number true positives must have been 100-17 = 83, as there
were 100 hits. Therefore we know that the search algorithm
found
83 of the 165 sequences it should have found, hence the
number of false negatives was 165-83 = 82. So, we know that
ntp = 83,
nfp = 17 and nfn=82. Using the equations in the notes, we
can calculate:
Sensitivity = ntp/(ntp+nfn) = 83/(83+82) = 83/165 = 0.50 (2
d.p)
Selectivity = ntp/(ntp+nfp) = 83/(83+17) = 83/100 = 0.83
Is This Answer Correct ? | 14 Yes | 0 No |
Answer / sulochana
difference between bio and cheminformatics and their uses
in drug discovery
Is This Answer Correct ? | 1 Yes | 9 No |
If a match from a sequence database search is reported to have an E-value of 0.0, should it be considered highly insignificant or highly significant?
Did shuffling of protein constituents occur between systems for multicomponent transport systems such as the atp-binding-cassette or complex protein secretion systems?
which instrument is most commonly used to observe the external features of grasshopper's abdomen?
How many bonds are present in CO2 molecule?
How long will a train 100m long traveling at 72kmph take to overtake another train 200m long traveling at 54kmph?
Suppose you used the NCBI Blast server to look for a match to a fruit-fly gene. Suppose further that the best alignment contained this section of an alignment: Hit from database: XXXXXXXXXXXXXXNFSTSQ User sequence: SLEAEAAPASISPSNFSSSQ What do the Xs signify?
What is a scoring matrix?
When X-Ray photons collide with electrons (a) They slow down (b) Their mass increases (c) Their wave length increases (d) Their energy decreases.
what is Glycomics?
Can independent origins be established for two families of transport systems having no sequence or motif similarities without three-dimensional structural data?
How to find a sequence of dna molecule?
What is computational biology?