Normalization of scores & bells curve

Normalization of Scores in Competitive Exams

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Normalization of scores is a widely used methodology to equalize scores from different sessions in competitive exams.
When an exam is held through multiple sessions, often for many days (e.g., IBPS exams, JEE), the question papers are going to be different for each session. The challenge now is to correlate the performances from different sessions, and this is when the normalization is used.



How normalization of marks is done?

Equipercentile methodology: This is a statistical procedure where raw scores of two different versions of the same test are considered equated if they correspond to the same percentile range (source:

P = 100 x [ ( N- r) / ( N – 1)] ———— (1)

P = Percentile rank of the candidate,

N =  Total candidates in shift,

r = Rank of the candidate in that shift.


The normalization of scores follows this equipercentile rule (1). Below is an example to illustrate how this works.

Session (I) has just 3 participants, and the table below shows their percentile score for the session (I).

Candidate Out of 100 Session rank Percentile
A 57 1 100%
B 42 2 50%
C 31 3 0%


Session (II) has 4 participants, their scores/percentiles are as shown below.

Candidate Out of 100 Session rank Percentile
D 35 1 100%
E 34 2 66.66%
F 32 3 33.33%
G 31 4 0%


Merging of sessions (I) and (II) based on the percentile scores would give the following ranking.

Candidate Percentile
A 100%
D 100%
E 66.66%
B 50%
F 33.33%
G 0%
C 0%


There can be other criteria like qualifying marks (or minimum marks). Those who do not secure the qualifying marks would not be considered during the ranking. A good percentile won’t help if you do not score the qualifying marks.

The cutoff scores (or percentiles) will be based on available vacancy & competition, and are decided at later stages. Historical cutoff values have no much significance except they can give some idea about the kind of competition had before.


How normalization helps students?

As we can see, it is all about scoring good marks in a session and being at the top. The ranking does not have any relation to the difficulty level of other sessions, you just have to be good among others from your session.


You can find chapterwise Bank exams and IBPS mock tests from the following links:

Bank Exam Chapterwise Mock Exams,

IBPS CRP/CWE Clerk (Prelims/Mains) Mock Exams,

IBPS PO Prelims Mock Exams.


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