Laboratory experiment: - carried out in a lab setting- Highest level of control - Loss of validity (esp.- Repeatable, therefore ecological validity) reliable if similar results - Demand characteristics. are produced- Can use sophisticated measuring equipment in a lab- More control over variables (could lead to knowing the cause/effect)
Field Experiment: - carried out in their natural environment• Improved ecological • Less control over IV and validity measuring DV. With• Reduction of demand addition of EV’s characteristics (though (extraneous variables) there may still be some) • Results cannot be generalised to other situations • Often more costly (as things have to be arranged outside – could inc. technical equipment)
Natural experiment: - IV is naturally occurring• Reduction of demand • Loss of control – The characteristics investigator doesn’t• The investigator doesn’t control the IV. intervene (however, the • A cause/effect presence of an relationship is difficult investigator could affect to establish ppts behaviour)
Correlation:- a term that refers to the extent to which values co-vary• Measures the strength • No cause/effect can be of relationships measured + 1 = perfect positive correlation -1 = perfect negative correlation
Observation: - No deliberate manipulation of the variablesNaturalistic: Observed in a natural environment, e.g. school or workplace.Lab-based observation: Labs can be ‘dressed up’ to look more natural, like a playroom, where children can be observed using a one-way mirror.
Observation – evaluation:• Good research can be • Control – cause/effect collected relationship cannot be• Ecological validity can established be good • Replication may be difficult due to variables • Observer effects/demand characteristics • Ecological validity may be lower • Costs can be high
Self report: Questionnaires:• Closed questions – • Simple Tickboxes • Cheap & quite quick• Open ended questions • Researcher doesn’t – ‘What are your views intrude on…?’ • Ambiguous questions• Leading questions – You could be misconstrued love this PowerPoint, • Leading Q’s don’t you? • Social desirability bias
Self report: Interviews:• Structured interviews – • Flexible (In set set of Q’s semi&unstructured)• Unstructured interviews – • Able to tackle personal Q’s aren’t decided in topics advance • Data can be• Semi-structured misinterpreted interviews – Some Q’s are • Time consuming pre-prepared, however • Interviewees may not be the investigator is free to able to convey their add more during the thoughts interview • Demand characteristics / social desirability bias
Case studies• In depth studies • Not generalisable -• Rich/interesting data they’re unique to the individual (or small group) • Findings may be subjective • Lots of data to chose from
Quantitative & Qualitative:Quantitative data:Tends to be numerical. Comes from things like tick boxes. (easily processed)Qualitative data:Data received from longer answer questions, often from interviews. (gives more detail)
Hypothesis’:• Directional hypothesis:Predicts the direction in which results will occur. E.g. ‘More words are recalled from a list when using rehearsal as a mnemonic technique than when no technique is being used.’• Non-directional hypothesis:Does not predict the direction of the outcome: ‘There is a difference in the number of words recalled from word lists presented with or without background music’• Null hypothesis:Would predict that the IV would have no effect. E.g. ‘Using mnemonic techniques will not improve memory’
Experimental design:Independent groups:Using different participants foreach condition of the experiment.Matched pairs:Matching each ppt with someonewho is similar to them, and placingthem in different conditions.Repeated measures:Exposing each ppt to eachcondition, so the ppts are(technically) their own controls.
DV and IV• Dependent variable:The variable that is assumed to be effected bythe IV. Changes in the DV are presumed to havebeen caused by the IV.• Independent variable:The variable which is manipulated by theexperimenter that is presumed to effect the DV.
Operationalising the variable:General statement: ‘Mnemonics improve memory’It means ‘narrowing down the research focus’So, figuring out the most simple IV and DV from a question.
Pilot study:• Small scale trial run of the actual experiment• Allows the investigator to identify flaws of the experiment• Tests for problems with - design of the experiment - Clarity of instructions for the ppts - Measuring instruments• Also allows a time scale of the actual experiment to be estimated
Extraneous variables:• Should (try to) be controlled so as not to affect the IV or the DV
Reliability & Validity:Reliability:Test whether something is reliable or not by doing repeats & seeing if similar results are gathered.Validity:Ecological validity – the extent to which the findings can be generalised to outside the research settingPopulation validity – the extent to which the findings can be generalised to other groups of people
Subjective & objective:Subjective:‘Based on or influenced by personal feelings, tastes, or opinions.’Objective:Data which is based on scientific information. Eg. Using blood samples would be considered objective.
Ethical issues:• Informed consent (though, sometimes presumptive consent is used on the basis that the investigator would think that they’d get consent)• Confidentiality• Right to withdraw• Deception• Protection from harm• Debriefing
Cost-benefit analysis:Is the cost of the experiment worth the amount of data we would get?
Types of sampling:1. Random sampling - Everyone in the population has an equal chance of participating. E.g. using a random number generator to find numbers2. Opportunity sampling - Unlikely to generate a representative sample, so investigation could be offered to everyone at a school, but then results couldn’t be generalised externally.3. Volunteer sampling - People sign up to the experiment (e.g. in Milgram 1960) Unlikely to be generalisable, as people who sign up are most likely to have a certain personality type
Demand characteristics:• Predicting what the experiment is going to measure and acting accordingly – which could hinder results• Acting out-of-character due to surrounding environment• Displaying social desirability biasInvestigator effects – When the investigator can get too involved in the experiment, causing a change in results
Measures of central tendency and dispersion:• Central tendency:- Mean (add up all no. Divide by amount of data)- Median (middle number when arranged numerically)- Mode (most frequently occurring no.)• Dispersion – ‘shows the spread of data’:- Range (highest score – lowest score)- Standard deviation
Points on the spec. Not covered in this PowerPoint:• How to reduce investigator effects• Be able to present quantitative data in appropriate graphs• Define types of reliability• Analyse and interpret correlation data• Define and know how to do content analysis• Present qualitative data in a ticklist/table• Pro’s and con’s of the matched pairs, independent measures, and repeat designs