India · Staff Selection Commission · civil-service · unverified source
Multi-tier computer-based exam; candidates for Junior Statistical Officer and Statistical Investigator posts take an additional statistics paper.
Built from Laisha's knowledge because the official page could not be opened or was not found during research (web search quota exhausted); confirm against the body's current notification before relying on it. These posts form the Subordinate Statistical Service of MoSPI, which runs the NSS fieldwork and price surveys. The tier structure has changed several times since 2017.
Official source: https://ssc.gov.in/
Original questions written to this exam's published syllabus and pattern. Not past papers.
1. Which statement describes a genuine limitation of statistics as a science?
D. It studies aggregates and cannot say anything certain about a single individual unit
Statistical laws hold for groups and on average; the mean yield of a variety says nothing certain about one plot. Biological variation is exactly what statistics handles, secondary data are routinely used, and sampling exists precisely to avoid complete enumeration.
Statistical Methods for Agricultural Sciences · Statistics: definition, uses and limitations; frequency distributions and curves
2. Disease severity on wheat leaves is scored 0 to 9 by eye. On which measurement scale are these scores?
D. Ordinal
The scores are ordered (9 is worse than 5) but the gaps between scores are not known to be equal, which is the definition of an ordinal scale. Nominal categories have no order at all.
Exploratory Data Analysis & Statistical Graphics · Types of data and measurement scales
3. In a survey of farms, P(A) = 0.6 that a farm grows maize, P(B) = 0.5 that it grows soybean, and P(A ∩ B) = 0.2 that it grows both. What is the probability that a randomly chosen farm grows neither crop?
C. 0.1
P(A ∪ B) = 0.6 + 0.5 − 0.2 = 0.9, so P(neither) = 1 − 0.9 = 0.1. The value 0.2 wrongly assumes independence, which the given P(A ∩ B) = 0.2 ≠ 0.3 rules out; 0.9 is the union itself.
Probability Theory · Sample spaces, sigma-fields and the axioms of probability
4. A binomial variable has mean 6 and variance 2.4. What is n?
B. 10
q = variance/mean = 2.4/6 = 0.4, so p = 0.6 and n = 6/0.6 = 10. 15 comes from taking p = 0.4 (confusing p with q); 6 confuses n with the mean.
Probability Distributions & Sampling Distributions · Discrete distributions: Bernoulli, binomial, Poisson, geometric, negative binomial, hypergeometric and multinomial
5. A weather chain has P(dry → wet) = 0.3 and P(wet → wet) = 0.6. If today is dry, what is the probability that the day after tomorrow is wet?
C. 0.39
P²(D, W) = 0.7 × 0.3 + 0.3 × 0.6 = 0.39, summing over tomorrow being dry or wet. 0.18 counts only the path dry-wet-wet.
Stochastic Processes · Markov chains: transition matrices and Chapman-Kolmogorov equations
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