Experiments - Design, method and types Flashcards
What 2 things are formed at the start any study?
Aim and hypothesis
DIFFERENCE between aim and hypothesis
An aim is the narrowing down on concepts to focus the research, they are general statements that outline purpose of an investigation.
HOWEVER, a hypothesis states the relationship between 2 variables as step in the theory
A hypothesis needs to be…
+The types
-Precise and testable
- Include the IV
Null, directional and non directional
Def of a non directional hypothesis + when to choose it
States a difference but not the direction (e.g positive negative..)
When there is little to no previous evidence
Def of directional hypothesis +when to choose one
States the relationship AND the direction expected
When there is substantial evidence supporting
What is the independent and dependant variable
I- manipulated/changed
D- thee one u measure
What are the 3 experimental designs
- Repeated measures
- Independent groups
- Matched pairs
Outline the independent groups design + evaluation
2 separate groups do the different condition in the ex. So they both experience 1 level of IV.
Their performance is compared.
S- order of effects is not a problem
W- Less economical bec 2X more people to collect = more time and money
W- more participant variables = less validity ( random allocation could be used to remedy this)
Outline the matched pairs design + evaluation
People are matched into pairs based if shared requirements. And one form each pair is placed in the 2 conditions = controls the confounding variables
S- demand characteristics and order of effects are minimised = only participated in 1 conditions
S- removes participant variable = more validity
W- Time consuming (practical)
W- They can still be unevenly matched
W-
Outline the repeated measures design + evaluation
ALL ppts are win both conditions
Mean scores are compared to if there is a difference
S- Ppts and variables are controlled = high validity
S- fewer ppts needed = less time and money spent
W- DEMAND CHARATERICTS bec ML to figure out the aims of the study
W- Order of effects - boredom and fatigue can cause deterioration = less validity or getting used to the activity
WHat r the 4 types of experiment
- Labratory
- FEILD
- Natural
- Quasi
Outline the laboratory experiment + evaluation + Example
Takes place in a controlled environment - not always a lab
The R controls the IV and DV
e.g Hanslly and Zimbardo
S- more control over confounding and extraneous variables = the DV i s only affected by the IV = high internal validity
S- Repeatable bec of high control = results can be tested = reliable
W- Lack of genralisablty bec of the hi control = ppts behaviour not natural (demand characteristics) = Low external validity
W- lacks mundane realism = doest represent IRL
Outline the Field experiments + evaluation + Example
IV is manipulate in a natural setting
E.g pavilion et al
S- Mundane realism - more than in the lab = results are more valid (external validity)
W- Loss of control of CV and EV = cause and effect is harder to establish = harder to replicate
W- Consent - ppts are unaware of the study so its not ethical
Outline the quasi experiment + evaluation + Example
Have the IV based on an existing difference between people like age or gender
S- often done in a controlled environment SO SAME AS LAB ( control )
W- cant randomly assign = Confounding variables
W- CANT BE CLAIMED THE IV MADE A OBSERVABLE CHANGE
Outline the Natural experiment + evaluation + Example
Like a lab field but the R has no control over the IV
The IV is NATURAL but the setting isn’t always
E.g Bickman (1974)/ Romanian orphan studies
S- provides opportunity to study things that are otherwise is unpractical
S- Hi external validity bec It IRL
W- Its rare = limits the generlisability ( Time, place etc)
W- ppts not randomly allocated = less sure if the IV had an impact
W- Lacks realism and has DM
