experimental designs

Question 1

independent groups

Answer 1

two separate groups of particpants experience two different conditions of the experiment

if there are two levels of the independent variable this means that all particpants experience one level of the IV only

performance of the two groups would then be compared

Question 2

limitation of independent group design

Answer 2

issue

particpants who occupy the different groups are not the same in terms of participant variables

if a researcher finds the mean difference between the groups on the dependent variable this may be more to do with partipcnat variables than the effects of the IV

these differences may act as a confounding variable which reduces validity of the findings

to deal with his problem you could use random allocation

Question 3

limiatation of independent group design

Answer 3

less economical than repeated measures

each particpants contributes a single result only

twice as many particpants would be needed to produce equivalent data to that collected in a repeated measures design

increases the time and money spent on recruiting particpants

Question 4

strenght of independent group design

Answer 4

order effects are not a problem whereas they are a problem in repeated measures designs

particpants are also less likely to guess the aims

Question 5

repeated measures

Answer 5

all particpants experience other conditions of the experiment

two would then be compared to see if there was a difference

Question 6

limitation of using repeated measure

Answer 6

biggest issue

each partipcnat has to do two tasks

order of these tasks may be significant - order effects

to deal with this you can use counterbalancing

repeated two tasks could create boredom or fatigue and may abuse deterioration in the performance in the second task

performance may also improve in the second task due to the effects of practice

order acts as a confounding variable

Question 7

limitation of repeated measures

Answer 7

particpants may work it the aim of the study when they exernce all conditions of the experiment

demand characteristics seem to feature in repeated measures

Question 8

strenght of repeated measures

Answer 8

partipcnat variables are controlled so have higher validity

fewer particpants are needed so less time spent recruiting them

Question 9

matched pairs

Answer 9

particpants are paired together on a variable or variables

one particpants from each pair would be allocated to a different condition of the experiment

this is an attempt to control for the confounding variable of particpants variable

Question 10

strenght of using matched pairs

Answer 10

particpants only take part in a single condition so order effects and demand characteristics are less of a problem

Question 11

limiataion

Answer 11

matching may be time consuming and expensive particularly if a pre test is required so it is less economical