Experimental Design + Internal Variables Flashcards
A strength of the independent groups design Is that order effects are completely controlled
E - Because participants in an independent groups design only take part in one condition, they never repeat an experimental task. This means order effects are not a problem. This helps strengthen internal validity.
limitation of the independent groups design Is it’s vulnerability to participant extraneous variables
E - The participants in each condition of an independent groups design are different. This means that participant extraneous variables, such as age, gender , or intelligence , may influence the dependent variable. This may undermine internal validity, especially if these EVs become confounding
strength of the repeated measures design is that it controls for participant extraneous variables
E - Participants in a repeated measures design take part in both conditions. This means there will be no differences between the conditions in respect of participant variables, such as age, gender, or intelligence. This prevents participant EVs becoming confounding and strengthens the study’s internal validity
A limitation of the repeated measures design is its vulnerability to order effects
E - Participants in a repeated measures design take part and both conditions. This means that they will always complete one of the conditions first and the other second. It’s possible that the order in which they complete the conditions could influence the dependent variable. For example, they may become bored the second time or potentially they may get better having had practice. This undermines internal validity, especially if order effects become confounding
limitation of the repeated measures design is its vulnerability to demand characteristics
E - Participants in a repeated measures design take part and both conditions. This means they will have more information about the experiment that in other designs, where they only complete one condition. This additional information increases the likelihood participants will guess the aim of the experiment and alter their behavior, either to please or frustrate the researcher’s aim (the please-u or screw-u effect).
strength of the matched pairs design is its ability to control for participant extraneous variables
E - In a matched pairs design, participants in each condition are carefully matched on variables such as age, gender, and intelligence. This matching helps reduce differences between the conditions, making it less likely that participant extraneous variables will become confounding. This strengthens the internal validity of experiments which use the matched pairs designs.
A strength of the matched pairs design Is that order effects are completely controlled
Because participants in a matched pairs design only take part in one condition, they never repeat an experimental task. This means order effects are not a problem. This helps strengthen internal validity.
A limitation of the matched pairs design is that it is time consuming and expensive for the researcher
E – Because matched pairs require different participants in each condition, then the researcher needs to recruit twice as many participants as a repeated measures design. This additional recruitment takes time and adds expense if participants are paid. Moreover, the process of matching participants on a particular individual characteristic adds additional time-consuming work not required for an independent groups design.
limitation of the matched pairs design is that it doesn’t offer a perfect control for participant extraneous variables
Although in a matched pairs design participants are matched, this doesn’t mean that they will be identical in every way. This means that even if the two conditions are equally matched on some types of participant EV (e.g., gender and age), they may be unmatched on another (e.g., IQ). As a result, it’s still possible for participant EVs to become confounding and undermine the study’s internal validity.
