Dr. Burke performs an experiment to determine how plants grow in a variety of temperature and moisture conditions. He runs five trials with five different groups of the same species of plant. The table below shows the results from his experiment.

Plant Group Temperature Moisture Average Plant Growth
Group 1 high high 2 in
Group 2 moderate moderate 6 in
Group 3 low low 0 in
Group 4 high moderate 3 in
Group 5 moderate high 4 in

After finishing the experiment, Dr. Burke explains that heat and moisture have no effect on plant growth. Based on the evidence shown in the table, is his explanation valid?