In “Effects of Plant Density on Tomato Yields in Western Nigeria” (Experimental Agriculture, Vol. 12(1), pp. 43–47), B. Adelana reported on the effect of tomato variety and planting density on yield. Four tomato varieties (Harvester, Pusa Early Dwarf, Ife No. 1, and Ibadan Local) were grown at four densities (10,000, 20,000, 30,000, and 40,000 plants/ha). Identify the

a. experimental units.

b. response variable.

c. factor(s).

d. levels of each factor.

e. treatments.

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