An experiment is designed to evaluate the effectiveness of fungicide and light on phlox plant growth. Fungicide is used with one group of phlox plants in a sunny region and fluorescent lamps are used with phlox plants in a shady region. Identify any problems that are likely to cause confounding.
◦ There is no way to know if any differences in effects from the two groups are attributable to the treatment (fungicide or fluorescent lamps) or the type of region (sunny or shady).
◦ There is no way to know if sunlight and fluorescent lamps produce similar effects on growth.
◦ There are no problems. This is a well-designed experiment.
◦ Experimenter effect.