Table 5. The advantages and disadvantages of experimental and non-experimental data collection designs .

^aMay be an issue in cross-sectional studies that require a long recall to the past such as dietary patterns, antenatal events, and life experiences during childhood.

Non-experimental	Experimental
Advantages
Quick results are possible	Comparable groups
Relatively less costly	Hawthorne and placebo effects mitigated
No recall biasa	Straightforward, robust statistical analysis
No time effects	Convincing results as evidence
Real-life data
Disadvantages
Observed, unobserved, and residual confounding	Expensive
	Time-consuming
	Overly controlled environment
	Loss to follow-up
	Random allocation of potentially harmful treatment may not be ethically permissible