Direct Answer: In multi-shift examinations conducted across different days, question paper difficulty inevitably varies slightly between shifts. To ensure complete fairness to candidates who face a harder shift, bodies like SSC and RRB use a Standard Normalisation Formula based on Mean and Standard Deviation. This formula scales raw scores so that a score in a tough shift is appropriately adjusted upward relative to an easy shift.
The Official Normalisation Formula
\(M_{ij} = \frac{\bar{M}_t^g - M_q^g}{\bar{M}_{ti} - M_{iq}} (M_{ij} - M_{iq}) + M_q^{gm}\)
Explanation of Formula Terms
| Term |
Mathematical Meaning & Scope |
| \(M_{ij}\) |
Normalised Score of the (j^{\text{th}}) candidate in the (i^{\text{th}}) shift. |
| \(\bar{M}_t^g\) |
Average marks of the top 0.1% candidates across all shifts combined. |
| \(M_q^g\) |
Sum of Mean and Standard Deviation of marks of all candidates across all shifts combined. |
| \(\bar{M}_{ti}\) |
Average marks of the top 0.1% candidates in the (i^{\text{th}}) shift (candidate's own shift). |
| \(M_{iq}\) |
Sum of Mean and Standard Deviation of the (i^{\text{th}}) shift. |
| \(M_{ij}\) (inside bracket) |
Actual Raw Score obtained by the candidate. |
| \(M_q^{gm}\) |
Mean marks of the shift with the maximum mean of all candidates across all shifts. |
How Shift Difficulty Affects Your Score
- If your shift was TOUGH:
- The average marks of your shift (\(\bar{M}_{ti}\)) will be low.
- The denominator \((\bar{M}_{ti} - M_{iq})\) decreases, which increases the multiplier factor.
- Result: Your raw score gets a significant positive boost (often +10 to +25 marks).
- If your shift was EASY:
- The average marks of your shift will be very high.
- The multiplier is lower, so the score increase is minimal or, in rare cases, normalized score matches raw score.
Common Myth Busted: Does Accuracy Affect Normalisation?
NO. A persistent student myth is that candidates with 100% accuracy get higher normalized marks than candidates with 80% accuracy who scored the same raw marks. The official normalization formula contains no accuracy variable. Normalization depends strictly on the statistical performance (mean and standard deviation) of candidates in that particular shift compared to all shifts.
