Types of Experiments and Sampling Methods
Laboratory experiments give you maximum control over variables and are easy to replicate, but they often lack ecological validity - basically, they don't reflect real life very well. Field experiments happen in natural settings, making results more realistic but harder to control.
Natural experiments study situations that occur naturally (like comparing children before and after a school policy change), whilst quasi experiments focus on characteristics that can't be randomly assigned, like personality traits or gender.
Your sampling technique massively affects whether you can generalise your findings. Random sampling gives everyone an equal chance of being selected, making your results more representative. Systematic sampling follows a pattern (like every 10th person), whilst stratified sampling ensures you get proportional representation from different subgroups.
Reality Check: Opportunity sampling (grabbing whoever's available) is the most common method in student research, but remember it can be quite biased towards certain types of people.