A factorial experiment was conducted to investigate the yield (BYIELD) of barley. Thirty-six

plots were divided into four blocks (BBLOCK). Three varieties (BVARIETY) were compared

at three dierent row spacings (BSPACE). The data are stored in Data File: Barley.txt

(a) Produce two exploratory data plots. With reference to the plots, describe how the means

may vary with variety and spacing. What statistical model is suggested?

(b) Fit a model that includes all main effects and the interaction between variety and spacing.

Produce relevant outputs and assess whether the interaction is signicant. Write an

informative summary that relates to the context of the question.

IT SHOULD BE DONE IN "R" .