Final answer:
A block design experiment is one where subjects are separated into similar groups and then randomly assigned to different treatments within those groups, effectively reducing the influence of lurking variables and ensuring reliable data is obtained. So the correct answer is option A.
Step-by-step explanation:
A block design experiment is a study in which subjects are separated into blocks or groups based on certain characteristics or similarities. The intention behind this is to account for variability among subjects that may affect the response to the treatments. Within each block, subjects are randomly assigned to the different treatments. This experimental design serves to reduce the potential impact of lurking variables by making sure that the only systematic difference between the blocks is the treatment applied by the researcher.
The correct definition that matches a block design experiment from the provided options is:
- A) a study in which subjects are separated into similar groups and then subjects within each group are randomly assigned to treatments.
This approach, along with the use of a control group and blinding, where neither the participants nor the researchers know who is receiving the active treatment, helps to maintain the integrity of the experimental design and ensures the collection of reliable data.