College aantekeningen
College aantekeningen Research Project (BT2103) Block 7
- Instelling
- Erasmus Universiteit Rotterdam (EUR)
College en Workshop aantekeningen van Research Project blok 7 inclusief screenshots van R-studio resultaten
[Meer zien]Voorbeeld 4 van de 57 pagina's
Voorbeeld 4 van de 57 pagina's
In winkelwagengesponsord bericht van onze partner
Verkoper
Volgen
Voorbeeld van de inhoud
Research ProjectLecture 8 – Experimentation
Todays Plan
• Causation
• Experimental design
• Developing experimental stimuli
• Experimental validity
Causation
Correlations vs. Causation
• Correlation is similar lines but they do not necessarily influence each other; causation
• E.g. visitors to Disneyland Paris and precipitation in Louisiana have similar lines but they do no cause or
influence each other
Reasons why X and Y can correlate
• X causes Y
• Y causes X = reverse causality
• Z causes both X and Y = third variable
• Spurious correlation
Reverse Causality = X appears to cause Y, but it is actually Y that causes X
• E.g. diversified firms tend to profit more; more profitable firms need to find ways to re-invest of its rather
than because diversification causes profitability.
,Third Variable = X appears to cause Y, but both X and Y are actually caused by Z
• The more toys a child has, the higher his or her IQ; both number of toys and IQ may be caused by family
resources such as income
Three conditions for causality
• Relationship between X and Y; X and Y vary together
• Time order; X cannot happen after Y
• Elimination of other possible causal factors; causes constant and controlled
Experimental Design
Basic features of between-subjects design
• Independent variable = manipulated across groups or between-subject
- Between-subject = one participant is assigned to one experimental conditions of IV
- Within-subject = one participant is assigned to several experimental conditions
• Dependent variable = measured
• Context = laboratory, online, field
• Controlling extraneous factors
- All things but independent variable are the same
- Participants randomly assigned
- Measurement of other variable under control
,Developing experimental stimuli
Stimuli = event or object to which a response is measured
• Can be visual, textual, verbal, space etc.
• E.g. visual stimuli – nutritional labelling
Confounding Variables = variables that have affected the results (DV) apart form the IV
• Can be extraneous that has been controlled
Experimental Validity
Internal validity
• Conclusions about the effects of IVs on DVs are valid
• Correct implementation of principles
• Lab studies are high in internal validity
External validity
• Conclusions generalized outside the experiment
e.g. lab participants to consumers
• Field studies are higher in external validity
Randomized Control Trial
• RCT in parallel groups = participants are randomly allocated into one of several conditions
• RCT in crossover = random allocation into different groups + DV measured several times
, • RCT in cluster = pre-existing groups of participants are randomly selected to receive and intervention
Designs facing threats to internal validity
• Quasi-experiment = assignment to the experimental conditions is not random
e.g. nutria-score in supermarket A vs. No nutri-score in supermarket B
• Pre-post = the DV is measured before and after an IV category
Replication experiments
1. See whether the effect is robust across situations
2. Build on previous experiments see whether your explanation makes sense
Field experimentation
• Testing customers reactions to changes
Online A/B testing
= refers to a randomized experimentation process wherein two versions of a thing are compared against each toher
to determine which performs better
Lecture 9 – introduction to linear regression
Today’s plan
• Intro into Regression Models
• Simple linear regression model
• Multiple linear regression model
• Individual assignment 3
Intro into Regression Models
Regression = an approach for modelling the relationship between a dependent variable (DV) and one or more
independent variables (IVs)
• Linear regression: DV is continuous / quantitative
• Logistic regression: DV is binary
Used to
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper felicehofte. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €10,39. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 53920 samenvattingen verkocht
Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen