Experimental designs Flashcards
what is an experimental method
method that looks at cause and effect
what is a variable
anything in the environment that can change between people and across situations
if we want to determine reading speed, what 3 things can be a variable
difficulty of word
distractions
lighting
we cannot control all variables, which 3 popular ones can we not control
personality
consent
brain
what are 2 ways we an control variables
standardisation- stopping any other factors from influencing the outcome
ensuring the process is kept as constant across conditions and participants
what is between subjects sample
participants take part in one condition
what is within subjects sample
participants take part in all conditions
what is an advantage of between subjects sample
reduced chance of fatigue/practise effects
what is a disadvantage of between subjects sample
requires more participants which all vary
what is an advantage of within subjects sample
reduced participants variability
what is a disadvantage of within subjects sample
fatigue/practise effects
what is a way to ensure allocation is random
based on test scores and paired with that person
which statistical test you use depends on what 3 things
whether data is parametric or not
number of experimental conditions
whether the design was within subjects or between
when you use an independent t-test, what 3 things are required
parametric data
between subjects
two conditions
what does an independent t-test examine
the difference between the means of the two conditions
what are the 5 stages you go through when looking at making a statisitical decision
what type of data is it parametric or non? what is the study looking at what type of design was used what was the hypothesis
if youre testing a relationship between 2 variables, the data is parametric and youve got within subjects, what test do you use
Related t test
if youre testing a relationship between 2 variables, the data is parametric and youve got between subjects, what test do you use
independent t test
if youre testing a relationship between 2 variables, the data is non-parametric and youve got within subjects, what test do you use
wilcoxon
if youre testing a relationship between 2 variables, the data is parametric and youve got between subjects, what test do you use
mann whitely
what 3 types of data can non parametric tests be used with
interval, ration and ordinal
what does non parametric data do
rank the data in order
does non parametric test create more or less reliable results
less
what is a wilcoxon test used for
testing scores before and after an observation e.g. before and after CBT
what is mann whitely used for
test the difference between 2 conditions
is mann whitely used with parametric data or non
non parametric
summary of wilcoxon
calculate the difference between conditions and rank the differences
summary of mann whitely
rank scores individually but across all conditions, add up ranked scores separately
what is ANOVA
analysis of variance between 3+groups
what does ANOVA do
compares 3 or more groups to see if there is a statistical difference between them
what are the assumptions when using ANOVA
interval data
normal distribution
homogeneity of variance
instead of ANOVA why dont we do multiple t -tests
3x more chance of type or error
