What is negative Marking in Prelims?

Negative marking means your marks will get deducted for each wrong answer.
In Civil Services Prelims, negative marking ratio is 1:3 and each question corresponds to 2 marks. Then on each correct answer, you will get +2 marks, and for each wrong answer, you will loose 1/3 x 2 = 0.67 marks

Strategy to handle Negative Marking:

1. If you cannot eliminate any of the answer choices, do not mark the answer.
Explanation:
By law of Probability, you get one answer correct and three answer incorrect for any four answers marked.
Thus, you gain 2 marks for a correct answer and loose 0.67 x 3 = 2 marks for three incorrect answers. Your net gain is 0.

2. If you can eliminate one of the answer choices, you should mark the answer.
Explanation:
By law of Probability, you get one answer correct and two answers incorrect for any three answers marked.
Thus, you gain 2 marks for a correct answer and loose 0.67 x 2 = 1.33 marks for two incorrect answers. Your net gain is 0.67 for three answers marked.

3. If you can eliminate two answer choices, you must mark the answer.
Explanation:
By law of Probability, you get one answer correct and one answer incorrect for any two answers marked. Thus, you gain 2 marks for a correct answer and loose .67 marks for one incorrect answer. Your net gain is 1.33 for two answers marked.

Even a good candidate has two take calculated risk. In every UPSC prelims, there will be 30 to 40 questions, for which candidates are confused among two or three answer choices.

By following too conservative strategy in marking answers, you may actually end up scoring less by 5 to 20 marks !!