Indian Statistical Service Examination (with Indian Economic Service) · India · Union Public Service Commission
Original practice questions written to the published syllabus · not past papersHow crop production is measured: area from complete enumeration, sample surveys and area frames, yield from crop-cutting experiments on randomly located plots, the Mahalanobis and Sukhatme debate on plot size, crop insurance CCEs, and newer satellite, model and smartphone-based methods.
In the exams: AICE-JRF Ag Stat Unit 5 'crop estimation surveys' (heavy); UPSC ISS Statistics III-IV official statistics (present); state DES statistical-officer exams (present)
How our questions for Indian Statistical Service Examination spread across the units of Crop Area & Yield Estimation: Crop-Cutting Experiments. Difficulty: 3 easy, 16 medium, 1 hard.
| Area statistics: complete enumeration, sample-based (EARAS, TRS) and area-frame methods | 4 | |
| Production = area x yield: the statistical structure | 3 | |
| Improvement of Crop Statistics (ICS) scheme and quality checks | 3 | |
| Crop-cutting for crop insurance: number of CCEs and technology-assisted CCEs | 3 | |
| Estimation of yield and its standard error at district and state level | 2 | |
| Plot size, shape and border bias in crop-cutting | 1 | |
| Yield estimation for horticultural and plantation crops | 1 | |
| Remote sensing, crop models and smartphone data in yield estimation | 1 | |
| Estimation of crop losses due to pests and diseases | 1 | |
| International practice: FAO guidelines and objective yield surveys | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A district's crop area is estimated with a CV of 2% and its yield, independently, with a CV of 4%. What is the approximate CV of estimated production?
A. 4.47%
For a product of independent estimates, CV(P)^2 is about CV(A)^2 + CV(Y)^2 = 4 + 16 = 20, so CV(P) is about 4.47%. Adding CVs (6.00%) overstates it; multiplying them has no basis.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
The EARAS scheme was set up mainly for states that:
C. Lack village land records for complete area enumeration
EARAS (Establishment of an Agency for Reporting Agricultural Statistics) created staff to enumerate area in a sample of villages in states, historically the permanently settled areas, without village land records.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
Why do very small crop-cutting plots tend to overestimate yield?
B. Doubtful border plants get included; small plots have more border
Border bias: investigators tend to include doubtful boundary plants, and the boundary-to-area ratio is larger for small plots.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
Three tehsils have rice areas of 30,000, 20,000 and 50,000 ha and mean yields of 2.8, 3.4 and 2.5 t/ha. What is the district yield?
B. 2.77 t/ha
District yield = sum(area x yield)/sum(area) = 277000/100000 = 2.77 t/ha. The simple average 2.90 ignores that the largest tehsil has the lowest yield.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
How is a state's average yield of a crop obtained from district figures?
D. State production divided by state area
State production is the sum of district productions; dividing by state area gives an area-weighted yield, not the simple mean of district yields.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
What is the main purpose of the Improvement of Crop Statistics (ICS) scheme?
C. Sample checks of area records and supervision of crop-cutting
Under ICS, central and state supervisors check crop inspection in a sub-sample of TRS villages and supervise a sub-sample of CCEs to detect and correct errors.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
Which agency supplies central supervisors for ICS sample checks in India?
B. The National Statistical Office's field operations
NSO (formerly NSSO) field operations staff, with state supervisors, carry out ICS checks.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
The threshold yield of an insurance unit is 1.92 t/ha and the crop-cutting yield this season is 1.5 t/ha. What percentage of the sum insured is payable?
C. 21.9%
Claim share = (threshold - actual)/threshold = (1.92 - 1.5)/1.92 = 21.9%. Dividing by actual yield gives 28.0%; 78.1% is actual yield as a share of threshold.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
What is the main difficulty in estimating losses due to one particular pest?
A. Separating it from other pests, weather and management
Yield reductions have many causes acting together, so attributing loss to one pest requires careful design or modelling.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
What is the purpose of the 50x2030 Initiative?
B. Building integrated agricultural survey systems
50x2030 supports low- and middle-income countries in building agricultural data systems that combine surveys and other sources.
Further reading: Sukhatme et al., Sampling Theory of Surveys with Applications; Panse, Estimation of Crop Yields (FAO)
Ten here, 20 in the app. The Laisha app has every practice question we have written to Indian Statistical Service Examination in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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