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ICAR AICE-JRF/SRF Specialised Agricultural Experiments: Cropping Systems, Animal & On-Farm Trials: practice questions

ICAR AICE-JRF/SRF - Agricultural Statistics, Computer Application, Bioinformatics (PhD admission and fellowship) · India · National Testing Agency for ICAR

Original practice questions written to the published syllabus · not past papers
10worked here, free
76written to this exam in this subject
9syllabus units

What this subject covers

The 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)

What ICAR AICE-JRF/SRF asks from it

ICAR AICE-JRF/SRF Agronomy (Unit 6)

Statistical analysis of cropping systems including intercropping: LER and related indices, system yield equivalents.

ICAR AICE-JRF/SRF Agricultural Statistics (Unit 4)

Crossover designs and their carry-over effects; correct experimental units.

Where the 76 questions fall

How our questions for ICAR AICE-JRF/SRF spread across the units of Specialised Agricultural Experiments: Cropping Systems, Animal & On-Farm Trials. Difficulty: 17 easy, 38 medium, 21 hard.

Analysis of intercropping experiments: LER, ATER and competition indices11
Sensory evaluation and panel experiments10
Repeated measures and growth-curve data9
Cropping-system experiments and system yield equivalents8
Animal experiments: switchover and changeover designs, carry-over effects8
Experiments with livestock: group feeding and pen as the unit8
Laboratory, greenhouse and pot experiments: pseudo-replication8
Long-term experiments and analysis over time7
Experiments in orchards and perennial crops7

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

1 · Analysis of intercropping experiments: LER, ATER and competition indices · hard

Maize yields 3.0 t/ha intercropped (50:50) and 4.0 t/ha sole. What is its relative crowding coefficient K?

  1. 1.33
  2. 0.33
  3. 3.0
  4. 0.8
Answer and working

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

2 · Cropping-system experiments and system yield equivalents · hard

Cropping systems are in main plots and nutrient levels in sub-plots. Against which error are systems tested?

  1. The sub-plot error of the nutrient levels
  2. The main-plot error
  3. The pooled error of all strata together
  4. The total mean square of the experiment
Answer and working

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

3 · Long-term experiments and analysis over time · easy

Why are archived soil and plant samples valuable in long-term experiments?

  1. They replace the need for annual yield records
  2. They allow later re-analysis by new methods
  3. They remove the need for randomisation
  4. They increase the number of replicates
Answer and working

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

4 · Animal experiments: switchover and changeover designs, carry-over effects · medium

What does Lucas's extra-period design add to a changeover design?

  1. A period with no treatment for every animal
  2. A second set of animals in parallel groups
  3. A random treatment in the first period
  4. A period repeating the last treatment
Answer and working

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

5 · Animal experiments: switchover and changeover designs, carry-over effects · medium

Why are the first days of each period often discarded?

  1. They are an adaptation phase
  2. They contain no treatment effect at all
  3. They are needed for randomisation
  4. They have the highest milk yields
Answer and working

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

6 · Experiments with livestock: group feeding and pen as the unit · medium

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)?

  1. A: 4, B: 20
  2. A: 4, B: 16
  3. A: 396, B: 396
  4. A: 8, B: 20
Answer and working

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

7 · Sensory evaluation and panel experiments · medium

What is the chance probability in a paired preference test?

  1. 1/3, tested one-sided
  2. 1/2, tested two-sided
  3. 1/4, tested two-sided
  4. 1/2, tested one-sided
Answer and working

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

8 · Sensory evaluation and panel experiments · hard

Why do consumer acceptance tests need far more assessors than trained-panel tests?

  1. Trained panels need no replication
  2. Consumer scores have no variance
  3. Consumer preferences vary widely
  4. Consumers cannot taste more than one sample
Answer and working

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

9 · Repeated measures and growth-curve data · hard

Why does a split-plot-in-time analysis of repeated measures often fail?

  1. It treats each plant as a block
  2. It assumes equal correlation between all dates
  3. It requires each date to be randomised
  4. It cannot include treatment effects at all
Answer and working

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

10 · Experiments in orchards and perennial crops · hard

A rootstock trial compares tree sizes. Why is interference especially important?

  1. Interference only matters in annual crops
  2. Large trees shade and out-compete small neighbours
  3. Rootstocks never differ in vigour
  4. Small trees always yield more per hectare
Answer and working

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

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Read the subject

Specialised Agricultural Experiments: Cropping Systems, Animal & On-Farm TrialsThe full study manual, free ICAR AICE-JRF/SRFFormat, sections and how it has changed

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Specialised Agricultural Experiments: Cropping Systems, Animal & On-Farm Trials for other exams

ASRB NET · IndiaASRB Agricultural Research Service · India

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