Indian Statistical Service (ISS) is one amongst the Central Civil Services. Annually, the Union Public Service Commission (UPSC) selects the candidates based on the All India Entrance Examination scores.
Candidates who wish to apply for ISS must have obtained a bachelor's degree with statistics/mathematical statistics/applied statistics as one of the subjects or a master's degree in statistics/mathematical statistics/applied statistics. Here is the ISS exam pattern and subject-wise preparation tips.

| S No | Subject | Marks | Time |
| 1 | General English | 100 | 3 hours |
| 2 | General Studies | 100 | 3 hours |
| 3 | Statistics-I (objective) | 200 | 2 hours |
| 4 | Statistics-II (objective) | 200 | 2 hours |
| 5 | Statistics-III (descriptive) | 200 | 3 hours |
| 6 | Statistics-IV (descriptive) | 200 | 3 hours |
The candidates will be tested on their grammar and vocabulary. The Commission will ask aspirants to write an essay in English. One should increase their grammar and vocabulary to score well in this paper. Aspirants are suggested to practise passages and precise writing.
The notification clearly states that daily observation is required. One should give special attention to the general knowledge topic, including the current events. Aspirants are suggested to pick any general knowledge book of their choice and start reading the history, Indian polity and geography chapters. Try to prepare notes while preparing for the general knowledge topics, which will help you a lot during the revisions.
As we said above, this is an objective paper that consists of 80 questions. Be strong in the computer application and data processing unit because it has more weightage. Though the chances of asking direct questions based on computers is low, one should not ignore them. Be familiar with all the statical methods.
This paper is also an objective paper and focuses more on the facts. The official statistics unit is very important in this paper. Aspirants should read about the national and international official statistical systems besides sector-wise statistics and national accounts. The methods of data collection and agencies involved in data collection in population census is important. Do not ignore theory of linear estimation and Gauss-Markov linear models in the linear models unit.
This descriptive paper is focused on conceptual knowledge. The sampling technique is the most important unit in this paper. One should learn each and everything about the National Sample Survey Office (NSSO). Be strong in the econometrics units because direct questions are expected. One should also give special focus to time series analysis in applied statistics.
This paper has a huge syllabus to cover, however, there is no need to panic if you are good with the basic concepts. The basics of C is very important and there is a chance direct questions will be asked. The wishart matrix is important in the multivariate analysis chapter. Never ignore concepts such as Gehan test, log rank test and design of clinical trials in survival analysis and clinical trial unit. The queuing models and notions of ageing are important in operations research and reliability.