Final answer:
To obtain internally valid causal estimates from a randomized evaluation, the conditions of Random Assignment, Control Group, and Comparable Groups must be met. These ensure that observed differences are likely due to the treatment and not pre-existing disparities or systemic differences.
Step-by-step explanation:
To obtain internally valid causal estimates from a randomized evaluation, certain conditions must be met. These include Random Assignment, having a Control Group, and ensuring Comparable Groups. Random assignment ensures that any systemic differences between groups are minimized, making it more likely that any observed differences after the experiment are due to the manipulation of the independent variable and not other factors.
A control group is essential, acting as a baseline by which the effectiveness of the treatment can be measured. This group receives a placebo or no treatment at all. When groups are comparable, they share similar characteristics before the study begins, further strengthening the causality of the findings since it reduces the chances that differences seen post-treatment are due to pre-existing disparities.
Other study designs like observational studies, surveys, and convenience sampling do not meet the criteria for establishing causality with the same level of certainty as randomized evaluations with control and comparable groups.