Dataset:  grasstrim.dat

Source: Z. Mallick (2010). "Optimization of the Operating Parameters
of a Grass Trimming Machine," Applied Ergonomics, Vol. 41, pp.260-265.

Description: Results of a 3^3 fractional factorial (L9 orthogonal
array) experiment to determine effects of 3 factors on hand-arm vibration
of a Grass Trimmer: Length of thread (1=100mm, 2=150, 3=200),
Engine speed (1=3000rpm, 2=4000, 3=5000), and Material of Handle (1=Wood,
2=Aluminum, 3=Acrylonitrile Butadiene Styrene (ABS) pipe).

Variables/Columns
Run number     8
Length (Coded)   16
Engine speed (coded)  24
Material of handle (coded)  32
Hand-arm vibration score    34-40