Quantitative Methods for Researchers Paul Cairns

Your objectives  Pretty general! – Landscape/area of experiments  Research topic? 2

My objectives  Three pillars – Experimental design – Statistics – Writing up  Need all three for good research 3

Why do we do experiments? 4

Philosophy of experiments  Test theories  Isolate phenomena  Severely test 5

Some consequences  Intrinsic value  Big is not always better  Narrow focus is essential 6

Experimental argument  Belief:X causes Y – A reason for looking  Try: change X and measure Y  Analyse carefully  Produce evidence 7

Statistical experiments  Natural variation – People, environment, stochastic  Systematic vs chance differences  No certainty 8

Devising an experiment  Research question (disposable)  One sentence  May use jargon  Answer is “yes/no” but probably “maybe”  Question suggests how to answer it QUAN, Paul Cairns

Devise a research question In groups of two or three, each have a go at a research question. Take turns to explain and be criticised. Be happy to be wrong/stupid. RQs are disposable. QUAN, Paul Cairns

Experimental Design  Addresses question  Validity  Design => Data => Results 11

Variables  Independent variable (IV, X) – Experimental conditions  Dependent variable (DV, Y) – quantitative  Confounding variables 12

Validity  Construct –measuring DV – possible, meaningful?  Internal – addressing question – confounds  External - generalisability  Ecological - realism 13

Fantasy abstract  Write an abstract for your experiment ( words) specifying: 1.What the question is 2.[Why it is interesting/important] 3.What was done in the experiment What IV and DV are 4.What significant results [would] show 5.What this means 14

Reading  Hacking, Representing and Intervening  Cairns, Cox, Research Methods for HCI: chaps 1, 6, 10  Harris, Designing and reporting experiments in psychology, 3rd edn 15