Experiments Flashcards
Independent variable
The variable that the researcher changes
Dependent variable
The variable that is measured
Extraneous variable meaning and issue
Any variable that could affect the DV that is not the IV
These could be an issue as they affect the ‘internal validity’
Extraneous or confounding?
When extraneous variables are not controlled by the experimenter, they become confounding variables that can damage the validity of the experiment (the experimenter does not notice the extraneous variable until before or after the experiment)
Situational variable:
Definition
How to control
Features of a research situation that may influence participant behaviour eg
- Order effects- (controlled by ABBA) The order the conditions are completed in could affect the results.
Practice effect means you do better in the second condition because you’ve practiced
Fatigue/ boredom means you do worse in the second condition because you are tired or bored
How to control situational variables
i. Standardise everything eg., noise levels time of day lighting instructions
ii. ABBA- Counterbalancing- half the participants complete condition A then B, the other half complete B then A
Participant variable:
Definition
How to control
(individual differences) The way in which each participant varies from the other, and how this could affect the results eg.,
Mood
IQ
Anxiety
Concentration
How to control participant variables
Depends on experimental design can use matched pairs
Investigator effects
Definition
How to control
-The experimenter unconsciously conveys to participants how they should behave (Experimenter Bias)
-The experimenter is often unaware of the influence they are exerting, but they have influence, nevertheless
How to control investigator effects:
Double blind design:
Both the participant and the person conducting the experiment are blind to the aims and/or hypothesis
Also the experimenter may be unaware which variable the participant is involved in
Inter-rater reliability
Independent raters rate same behaviour as researcher- check for agreement
Demand characteristics
Definition
How to control
Demand characteristics-
If participants know/ guess the experimenter’s intention they may change their behaviour accordingly
They may think they are doing this to be helpful- but its not actually helpful,
How to control demand characteristics:
Single blind design
The participant is unaware of which condition they are in or the
research aims. This prevents the participants from seeking
clues about the aims and reacting to them
Deception
Lying about the aims of the study and/ or using distracting questions
Internal validity
A validity concerned with what goes on inside a study. Is the researcher measuring what is intended. Includes control of variables to ensure changes in DV are solely due to IV.
Hypotheses meaning
Precise and testable statement of prediction about the outcome of an experiment. States the relationship between the variables to be investigated
Experimental/ alternative hypothesis
Predicts there will be a difference/ relationship
This is either directional or non directional. Directional predicts the direction of the results but non-directional does not. Non directional is also known as two tailed as the results could go either way, and directional is known as one tailed.
Null hypothesis
Predicts there will not be a difference/ relationship
Four elements of a good hypotheses
All conditions mentioned
Operationalised (measurable)
Future or present tense
Difference (bar chart) or relationship (line graph)
Experimental design
the way in which participants are allocated to different condition in an experiment for comparison
Questionnaire definition
Set of written questions – designed to collect information. Can discover what people think or feel (no guessing work like observations). Always pre-determined (structured). Can provide either qualitative data or quantitative data. It is used to assess the DV.
Structured interview
An interview where the questions are decided in advance.
Can be easily repeated because the questions are standardised.
Different people can be compared due to the standardised questions
Answers are easier to analyse due to being predictable
Unstructured interview
The interview starts out with general aims and sometimes questions, the interviewee’s answers guide subsequent questions
More detailed information can be obtained
Requires interviewer with more skill because the interviewer has to develop more questions
Questions may lack objectivity due to the quick nature of creating the questions
More expensive due to the need for experienced interviewer
Interviewer bias
Naturalistic vs controlled
Naturalistic - takes place in the setting or context the target behaviour would usually occur
Controlled - there is some control over variables to observe effects and control extraneous variables
Overt vs Covert
Overt - participants aware that the observer is present/ Covert - the participants unaware that the observer is present
Participant vs non participant
Participant - observer joins in with participants and behaviour being observed
Non participant - observer stays separate and observes from a distance
Structured vs unstructured observation
Unstructured observation- accounts of data in rich detail, researcher writes down everything they see
Structured observation- specific acts that make up the target behaviour that are clearly defined, they allow the researcher to quantify their observations using a pre determined list of behaviours and sampling methods
Sampling methods
Event sampling- counting the number of times a particular behaviour occurs in a target individual or group
Time sampling- recording a behaviour within a pre established time frame. Eg making a note of what a specific player is doing in a football match for 1 minute every 10 minutes (using a behavioural checklist)
Pilot Study
A pilot is a small-scale run of the actual investigation and may involve only a few participants
Pilots can be run for experiments, self report measures and observations.
Psychologists conduct pilot studies to test the experiment’s effectiveness and make improvements before the larger-scale version.
This allows them to identify issues early, which can then be rectified, saving time and money in the long run
Any part of the study could be measured, for instance the validity, how long it takes, if the instructions are too complicated etc
The 3 experimental designs
Repeated measures
Independent groups
Matched pairs
Social desirability bias
Participant answers in a way they deem socially acceptable
Population
A group of people who are the focus of the research is interest from which is smaller sample is drawn
Sample
A group of people who take part in a research investigation. The sample is drawn from a target population, and his presumed to be representative of that population.
Generalisation
The extent to which findings and conclusions from a particular investigation can be broadly applied to the population. This is made possible if the sample of participants is representative of the population.
Random sample
All members of the target population have an equal chance of being selected.
A complete list of all members of the target population is made. All of the names are assigned a number. The sample is generated through a random number generator.
Good: free from researcher bias
Bad: time consuming, may be unrepresentative
Systematic sample
Every nth member of the target population selected. The list of people in the target population of sorted into a sampling frame. A sampling system is nominated, e.g. every sixth person or a random interval to reduce bias.
Good: avoids researcher bias, usually representative
Stratified sample
The composition of the sample reflects the proportions of people in certain subgroups within the target population or the wider population. The researcher first identifies the different strata that can make up the population then the proportions that are needed for the sample to be representative of worked out. Finally, the participants that make up the stratum are selected using random sampling.
Good: Avoids researcher bias, more representative
Bad: the identified strata cannot reflect all the ways that people are different to complete representation is not possible. Time consuming
Opportunity sample
Research has decided to select anyone who will be willing and available to participate in the experiment. The research asks, whoever is around at the time of their study for example in the street.
Good: fast and convenient
Bad: Unrepresentative of target population, findings cannot be generalised. Researcher bias as researchers may avoid people they don’t like the look of
Volunteer sample
Participant select themselves to be in the sample (self selection)
The researcher may place an advert in the newspaper, or in the common room noticeboard .
Good: fast and cheap
Bad: volunteer bias, may attract a small unrepresentative group of people
Case study
In-depth investigations of a single person, group, event or community. Typically, data is gathered from a variety of sources by using several different methods.
Positives:
Provides detailed (rich qualitative) information
Provides insight for further research
Permits investigation of otherwise impractical or unethical situations
Negatives
Provides little basis for generalisation of results to the wider population
Researchers’ own subjective feeling may influence the case study (researcher bias)
Difficult to replicate
Time-consuming and expensive
Natural Experiment
When the researcher takes advantage of a naturally occurring independent variable, setting does not have to be natural
Strengths:
It can have ecological validity. Can be useful in studying phenomena that is unethical to manipulate, eg a school shooting
Weaknesses:
More difficult to control extraneous variables making it harder for other researchers to replicate. Researcher has no control over independent variables
Field Experiment
Conducted in a real, everyday setting (not a literal field)
Strengths:
There is lower chance of demand characteristics occurring.
Weaknesses:
Can be very time consuming and expensive
Quasi Experiment
When the researcher does not control the IV, the IV is a pre existing difference between participants eg gender or age. Can occur in lab conditions
Strengths:
Often carried out in lab conditions so has high control.
Weaknesses:
Participants cannot be randomly allocated into groups so there is a strong likelihood of confounding variables.
Lab experiment
They are conducted in a highly controlled environment, not always a literal lab
Strengths:
Uses a standardised procedure that is easy to replicate. Highly controlled which makes accurate measurements possible. High control allows cause and effect to be established.
Weaknesses:
It is likely that participants will know they are being studied which can cause the problem of Hawthorne effect. Demand characteristics can occur. May not reflect real life and therefore could lack ecological validity.
Consent Form
• Explains what will happen, and what the participants are asked to do
• Research aims
• How long it will take
• Reminds them that they can withdraw at any time
Any data collected will be kept confidential
Debrief
• A debrief occurs at the end of an experiment
• It should contain the true details of the experiment, including aims, the existence of other experimental groups or conditions
• Participants must be told what their data will be used for and be given the right to withdraw their data (especially for retrospective consent)
Participants may require counselling in extreme cases, which the researcher should provide
Debrief
• A debrief occurs at the end of an experiment
• It should contain the true details of the experiment, including aims, the existence of other experimental groups or conditions
• Participants must be told what their data will be used for and be given the right to withdraw their data (especially for retrospective consent)
Participants may require counselling in extreme cases, which the researcher should provide
Presumptive consent
a similar group of people are asked if the study is acceptable. If it is agreed then the consent of the participants is presumed
Prior General Consent
participants give permission to take part in a number of studies, including one involving deception, they are consenting to being deceived
Retrospective Consent
they are asked after they have already taken part
