In an experiment on growing sweet peas, a team of students selected two factors at four levels each and recorded Weight, Stem Length, and Root Length after six days of growth. They grew plants using various amounts of Water and Quickgrow solution, a fertilizer designed to help plants grow faster. Each factor was run at four levels: little, some, moderate, and full. They grew two plants under each of the 16 conditions. The response variable was Weight in mg.

An interaction plot shows

1200 1000 Moderate Full Weight (mg) Water 800 Some Levels 600 Little Full Little Moderate Some Amount of QuickgrowAnalysis of Variance for Weight Sum of Mean Source DF Squares Square F-ratio P-value Water 246 255 82 084.8 2.5195 0.0948 QS 00 w w 827 552 275 851 8.4669 0.0013 Water X QS 176 441 22 055.1 0.6770 0.7130 Error 16 521 275 32 579.7 Total 31 1 771 523