Disadvantages: * Elimination of extraneous variables is not always possible. * Experimental situation may not relate to the real world. * It may be unethical or impossible to randomly assign people to groups. Eg. : Unethical to deliberately deprive children of sleep. * Impossible (expensive) to observe ‘jetlag’ by sending people on world trips. * Unethical to experiment on forms of punishment on children by subjecting them to punishment. * Advantages and Diadvantages of the Quantitative Observational Design. Advantages: *
Quantitative observational designs allow variables to be investigated that would be unethical, impossible or too costly under an experimental design. Some kinds of behaviour can only be observed in a naturalistic setting. Disadvantages: * Cannot infer such a strong cause and effect relationship because there is or greater chance of other variables affecting the results. This is due to the lack of random assignment to groups. * Cannot replicate the findings as the same situation will not occur naturally again. * Quantitative Observational does not allow generalisation of findings to the general population. * Observer bias may influence the results.