Designing an experiment Lesson 5 http studycomacademylessonquasiexperimentaldesignsdefinitioncharacteristicstypesexampleshtml Define Quasi experiment Comparison between repeated measure and independent samples design ID: 564153
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Slide1
Research methodsDesigning an experiment
Lesson 5Slide2
http
://study.com/academy/lesson/quasi-experimental-designs-definition-characteristics-types-examples.html
Define Quasi experiment.Comparison between repeated measure and independent samples design
O
n the whiteboard…Slide3
RecapSlide4
On the whiteboards.Define the following:
Extraneous/confounding variables relevant to experiments:
Participant variablesPsychological qualities of p’s that might affect their performance on the task
D
emand characteristics
All cues, which convey to the p’s the purpose of the experiment.
O
rder effects
order
of the conditions having an effect on the participants’ behavior
.
Investigator effects
Any effects on the investigator’s behaviour on the research outcome. Slide5
Define the following controls…
Counterbalancing
An attempt to control for the effects of order in a repeated measures design: half the participants experience the conditions in one order, and the other half in the other order.
Randomisation
Use of ‘chance’ in order to control for the effects of bias
Standardisation
(instructions, environment, experience
)
Ensuring all participants are subject to the same experience
Single
& double blind
procedures
Single blind procedure: participant does not know
the condition under
which they are
being tested
Double blind procedure: experimenter does not know the condition under which the p’s are being testedSlide6
How could you control for
Participant variables?
Random allocation of p’s to conditionsPre-test of participantsRepresentative allocationOrder effects?
Counterbalancing
Complex counterbalancing
Randomisation of condition order
Randomisation of stimulus items.
Elapsed timeSlide7
Hypotheses
What is a
hypothesis?testable, predictable statement.States the relationship between the variables being testedWhat are the qualities of a good hypothesis
?
Testability
based on knowledge
Simple
Operational
Open doors for further enquiry.Slide8
What
is a one tailed and two tailed hypothesis?
A one tailed (directional) hypothesis states the direction in which the results are expected to go
People who have plentiful sleep (an average of 8 hours or more hours per night over a period of one month) have better marks in class tests than people with a lower sleep average.
A
two
tailed
(non- directional
) hypothesis
states that there is a difference between two conditions but does nor state the direction of the difference.
People
who have plentiful sleep (an average of 8 hours or more hours per night over a period of one month) have
different
marks in class tests than people with a lower sleep average.Slide9
Decide whether the following hypothesis are one or two tailed
Alcohol affects reaction
timeMen who have beards are perceived as older than clean-shaven men
The quality of beer affects bar
takings
The
faster you type the more mistakes you make. Slide10
Ethics
Please complete Ethics homework in your green RM pack
For next Tuesday Slide11
Task: Experimental design
For each of the studies answer the following questions:
Identify the independent variableIdentify the dependent variable
Identify the experimental design
What strength does this experimental design have in this study?
What limitation does this experimental design have in this study
?
Write a directional hypothesis for the experiment.Slide12
Loftus and Palmer (1974) investigated whether leading questions affect answers to speed questions. Participants were shown films of traffic accidents; all groups were shown the same films. They were then asked to give a general account of what they had just seen and asked a series of questions about it. The critical question asked was ‘About how fast were the cars going when they HIT each other?’ The word ‘HIT’ was replaced by either ‘SMASHED’, ‘COLLIDED’, ‘BUMPED’ or CONTACTED’. Each group was asked with a different word. The results suggested that participants recall was influenced by the speed word used. The word ‘smashed’ led to the fastest speed estimate (mean = 40.8 mph) and the word ‘contacted’ the slowest (mean = 31.8 mph).Slide13
Bandura et al (1961) aimed to see if behaviour that is observed will be repeated. Participants (children aged 3-5) were divided into three groups. Individuals were matched in the three groups according to their aggression levels that existed before this study began. Group one observed an aggressive adult model hitting a
Bobo
doll; group two observed the model acting non-aggressively and group three observed no model. All participants were then placed in a room with a Bobo doll and their behaviour was observed. Group one acted most aggressively. There was little difference between the aggression shown by groups two and three. The conclusion was that aggressive behaviour shown by a role model was imitatedSlide14
Peterson
and Peterson (1959) investigated how long simple information stayed in short term memory (STM) without repetition. On each trial the participants saw a trigram, which consisted of three consonants (e.g. BVM, CTG). A different trigram was used for each trial and each participant took part in each trial. They were asked to recall each trigram after a delay of seconds: 3,6,9,12,15 or 18. Once they were shown the trigram they had to perform an interference task, which prevented repetition of the trigram in STM. They were shown a random three digit number (e.g.866, 532) and had to count backwards from it in threes. After the appropriate time delay the trigram had to be recalled. The longer the time delay, the more the forgetting occurred in STM. After 3 seconds 80% of participants remembered the trigram, but after 18 seconds only 10% of the participants remembered the trigram. Slide15
Please answer the exam question on the handout given to you
Exam question 2013Slide16
Designing an experiment
What points do you need to consider when designing an experiment?Slide17
Class experiment
M
usic can affect the ability to concentrate
.
Design an experiment
that could be carried out in a classroom to test the effects of two
different kinds
of music on a task requiring concentration
(e.g.
word search)
.
You
must
use a repeated measures design.
You
should:
fully
operationalise
the independent and dependent variables
provide details of how you would control extraneous variables
describe
the procedure that you would use.
We will be carrying out the experiment so enough detail must be given in order for the class to do this!