Final answer:
An experiment's report must include a discussion on random or systematic errors. Random assignment in experimental design ensures that any differences observed are due to the treatment rather than pre-existing differences or chance. Proper experimental design isolates the explanatory variable to demonstrate its effect on the response variable.
Step-by-step explanation:
No report of an experiment is complete without an understanding of the source and experimental errors, which may be random or systematic.
In the context of experimental design, researchers use random sampling and random assignment to control for lurking variables and ensure that the groups are statistically equivalent. Random assignment is a process whereby all participants have an equal chance of being placed into either the experimental or control group. This method helps to distribute potential confounding variables evenly across both groups, thereby reducing the impact of these variables on the experiment's outcome.
Experiments aim to investigate the cause-and-effect relationship between an explanatory variable (the manipulated variable) and a response variable (the outcome variable). If designed properly, the only difference between the experimental and control groups should be the treatment administered, allowing any observed changes in the response variable to be attributed to the explanatory variable.