Introduction:
In the UPSC examination, marks are deducted for incorrect answers. This is to discourage random guessing and ensure that candidates have a thorough understanding of the subjects they are being tested on. The marking scheme for incorrect answers is called negative marking.

Explanation:
Negative marking is a system where marks are deducted for incorrect answers. This scheme is implemented in order to penalize candidates who guess the answers without having proper knowledge of the subject. It aims to encourage candidates to only attempt questions they are confident about, rather than guessing randomly.

How many marks are deducted?
The number of marks deducted for incorrect answers varies depending on the examination. While some exams deduct a fixed number of marks for each incorrect answer, others deduct a fraction of the marks allotted to a particular question. Let's explore some examples:

1. Civil Services Examination (UPSC):
- For objective type questions, there is a penalty of one-third (0.33) of the marks allotted to the question for each incorrect answer.
- If a question is left unanswered, there is no penalty.

2. Common Admission Test (CAT):
- For multiple-choice questions, there is a penalty of one mark for each incorrect answer.
- For non-multiple-choice questions, there is no negative marking.

3. Graduate Aptitude Test in Engineering (GATE):
- For multiple-choice questions, there is a penalty of one-third (0.33) of the marks allotted to the question for each incorrect answer.
- For numerical answer type questions, there is no negative marking.

Impact of negative marking:
Negative marking can have several implications for candidates:

- It forces candidates to think critically and make informed choices rather than guessing randomly.
- Candidates need to be confident about their answers and have a strong understanding of the subject matter.
- It prevents candidates from attempting all questions without considering their accuracy, thus ensuring a fair evaluation process.
- It encourages candidates to focus on accuracy rather than attempting all questions in order to maximize their score.

Conclusion:
Negative marking is a practice implemented in various competitive examinations, including the UPSC, to discourage random guessing and assess the candidate's knowledge and understanding of the subject matter. The specific number of marks deducted varies depending on the examination, but the underlying objective remains the same - to promote accuracy and discourage blind guessing.