Final answer:
Manipulation of the dependent variable is not an experimental design issue, as the dependent variable is measured, not manipulated. Key issues include the manipulation of the independent variable, control over extraneous variables, and random assignment of subjects to treatments to avoid lurking variables. The correct option is d.
Step-by-step explanation:
The correct answer to the question 'All of the following are experimental design issues EXCEPT' is d) manipulation of the dependent variable. In an experimental design, the dependent variable is the variable being tested and measured, not manipulated by the experimenter. It's the independent variable that the experimenter manipulates to determine if it causes any change in the dependent variable.
In terms of experimental design, one key aspect is the selection and assignment of subjects to treatment groups. This must be done in such a way as to ensure randomization to control for any potential lurking variables. This ensures that any detected differences in outcomes are likely due to the treatment itself rather than differences between groups of subjects.
Another critical element of experimental design is control over extraneous variables. These are variables other than the independent variable that could influence the outcome of the experiment and need to be controlled to prevent them from affecting the results.
The manipulation of the independent variable is essentially the core of any experiment, as this is the variable that the researcher changes to observe the effects on the dependent variable. For example, if the effect of a new medication is being tested, the medication dosage level would be the independent variable that is manipulated.