Pumpkin patch: suppose we plant pumpkins in a garden where half of the plants are shaded. then, to test a new fertilizer, we fertilize the plants in full sun and do not fertilize the plants in the shade. in the fall the fertilized plants yield more, bigger, and prettier pumpkins.
which of the following did we fail to include in the experimental design?
(1) establish a control group
(2) direct control of confounding variables
(3) compare groups of the explanatory variable
(4) establish measurable outcomes to determine the effectiveness of the explanatory variable