ASRB NET - Agricultural Statistics (and Computer Application / Bioinformatics) · India · Agricultural Scientists Recruitment Board (ICAR)
Original practice questions written to the published syllabus · not past papersThe experiments that do not fit a textbook layout: intercropping and its indices, long-term fertiliser and cropping-system trials, animal and changeover feeding trials, repeated measures on the same plants or animals, on-farm and participatory trials, and sensory and laboratory experiments.
In the exams: AICE-JRF Agronomy Unit 6 'statistical analysis for cropping systems including intercropping' (heavy); AICE-JRF Ag Stat Unit 4 crossover designs (present); ASRB NET Ag Stat (reported)
ASRB NET / ARS Agricultural Statistics
Applied design choices for animal, orchard, greenhouse, on-farm and sensory experiments; pseudo-replication; repeated measures.
How our questions for ASRB NET spread across the units of Specialised Agricultural Experiments: Cropping Systems, Animal & On-Farm Trials. Difficulty: 18 easy, 46 medium, 23 hard.
| Analysis of intercropping experiments: LER, ATER and competition indices | 10 | |
| Sensory evaluation and panel experiments | 10 | |
| Repeated measures and growth-curve data | 9 | |
| Experiments with livestock: group feeding and pen as the unit | 9 | |
| On-farm and participatory trials | 9 | |
| Cropping-system experiments and system yield equivalents | 8 | |
| Long-term experiments and analysis over time | 8 | |
| Animal experiments: switchover and changeover designs, carry-over effects | 8 | |
| Experiments in orchards and perennial crops | 8 | |
| Laboratory, greenhouse and pot experiments: pseudo-replication | 8 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Maize yields 3.0 t/ha intercropped (50:50) and 4.0 t/ha sole. What is its relative crowding coefficient K?
C. 3.0
K = Y_ab Z_ba / [(Y_aa - Y_ab) Z_ab] = 3.0 x 0.5/(1.0 x 0.5) = 3.0.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
Cropping systems are in main plots and nutrient levels in sub-plots. Against which error are systems tested?
B. The main-plot error
Systems vary between main plots; their error is error (a), as in any split plot.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
Why are archived soil and plant samples valuable in long-term experiments?
B. They allow later re-analysis by new methods
Archives let new questions be answered from past states of the system.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
What does Lucas's extra-period design add to a changeover design?
D. A period repeating the last treatment
Repeating the last treatment makes direct and carry-over effects orthogonal.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
Why are the first days of each period often discarded?
A. They are an adaptation phase
Discarding adaptation data reduces carry-over influence.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
Design A uses 2 pens of 50 birds per diet; design B uses 5 pens of 20 birds, with 4 diets. How many error df does each have (CRD)?
B. A: 4, B: 16
A: 8 pens - 4 = 4; B: 20 pens - 4 = 16. Birds are not units.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
What is the chance probability in a paired preference test?
B. 1/2, tested two-sided
Either sample may be preferred, so the test is two-sided with p = 1/2.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
Why do consumer acceptance tests need far more assessors than trained-panel tests?
C. Consumer preferences vary widely
Large between-consumer variation requires large samples for precise means.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
Why does a split-plot-in-time analysis of repeated measures often fail?
B. It assumes equal correlation between all dates
Compound symmetry rarely holds; correlation usually declines with time separation.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
A rootstock trial compares tree sizes. Why is interference especially important?
B. Large trees shade and out-compete small neighbours
Treatments that change tree size bias neighbours' performance unless guarded.
Further reading: Gomez and Gomez, Statistical Procedures for Agricultural Research; Mead, Curnow and Hasted, Statistical Methods in Agriculture and Experimental Biology
Ten here, 87 in the app. The Laisha app has every practice question we have written to ASRB NET 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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