Question

Three varieties of native grass are being studied for the amount of dry matter produced per square meter over a growing season. In the study region, grass is usually cut two or three times each growing season. The goal is to identify the combination of grass & cutting schedule that produces the greatest amount of dry matter during one growing season. At one location, three similar 2 m x 1 m plots were obtained. Each variety of grass was randomly assigned to one of the three plots and then planted on the entire selected plot using equal amounts of seed uniformly spread out on each plot. Each plot was divided into two 1 m2 half plots. One half plot was randomly assigned to be cut twice with other half plot to be cut three times. This process was repeated at 4 additional locations for a total of 5 locations. All plant material harvested from each half plot at each cutting was then dried and individually weighed (kg/m2). These weights were then totaled for each half plot. Describe the treatment structure of the experiment including the treatment factor(s) and their corresponding levels 2/ Identify the experimental unit(s) and the observational unit. Specify the total number of (each size of) experimental units used in the experiment 3/ Identify the design structure and any factors associated with the design e structure (e.g. blocking factors). 4/ Classify the response on the OU as nominal, ordinal, interval or ratio

Answer 1

(1)

Locations: four level , L1, L2,L3,L4

Varieties: Three level , V1,V2,V3

Cutting: C1,C2

Observational unit: Harvested Dry Matter

Experimental units are varieties and cuttings

2) Identify the experimental unit(s) and the observational unit. Specify the total number of (each size of) experimental units used in the experiment

required answer =total number=4*3*2=24

(3) This is split-plot design. The blocking variable is variety of grass

	L1				L2
V1	V2	V3		V1	V2	V3
C1	C1	C1		C1	C1	C1
C2	C2	C2		C2	C2	C2
	L3				L4
V1	V2	V3		V1	V2	V3
C1	C1	C1		C1	C1	C1
C2	C2	C2		C2	C2	C2

(4)  Classify the response on the OU as nominal, ordinal, interval or ratio

answer is : Ratio

nominal variables are used to “name,” or label a series of values. Ordinal scales provide good information about the order of choices.The ratio type takes its name from the fact that measurement is the estimation of the ratio between a magnitude of a continuous quantity and a unit magnitude of the same kind . A ratio scale possesses a meaningful (unique and non-arbitrary) zero value.