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40 Cards in this Set

  • Front
  • Back

Inus condition

an insufficient but non-redundant part of anunnecessary but sufficient condition (Ex. A lighted match in starting a forestfire)

Counterfactual model-

something contrary to fact(ex. the difference between a control group and the experiment group. Whataffect the action had on the control group) This is an ideal but it isimpossible to get a perfect representation.

Rubins casual model

a modelused for cause inference in case-control studies

John Stuart Mill-

cause and effect are relatedif (1) the cause preceded the effect,(2) the cause was related to the effect (3) we can find no plausiblealternative explanations for the effect other than the cause. Therefore experimentsare the best scientific method for this end.

Confound

a third variable that explains a correlation between two other variables

Popper-

it’s easier to find falsifying evidence than toprove something

Kuhn Falsification dependson two assumptions

1. The causal claimis perfectly specified.2. Falsification requires measures that areperfectly valid reflection of the theory being test

Cronbach – two problems withgeneralization

1. Generalizing tothe “domain about which the questions is asked”, which he called UTOS 2. Generalizing to“Units, Treatments, Variables, and settings not directly observed which hecalled *UTOS

Correspondence Theory

knowledge claim is true if it corresponds to theworld – example we can tell it is raining if we see rain

Coherence theory-

says that a claim is true if it belongs to acoherent set of claims – If A is true then B is true then C is true so A causesB

Pragmatism-

a claim is true if it is useful to believe thatclaim – “electrons exist” because going off that brings meaning andpredictability to the observations

Three Principles ofQuasi-experimentation

1.Identification and studyof plausible threats to internal validity2. Primacy of Control byDesign (To eliminate threats of internal validity (by design or by statistics)3. Coherent Pattern Matching

Predictions from

In this order:


1. Abstract Casual Theories


2. Authorities Prescription/assertions


3. Assertions of interest groups


4. No theories

Five factors

n -semi fixed


delta - can control by choosing a context where it is expected to be large


Correlation - Can control by incorporating/ ruling out other causes (e.g., Vsand Zs)


alpha - fixed


beta - risk of failing

with R XO


and R O


How do you improve

a. ANCOVAto estimate and remove difference due to V

Non random asssignment


How do you improve

Make groups more equivalent by deleting non overlappingobservations before trt

Main contributions to research

1. New Data


2. New estimation


3. New Theory (or Problem)

Different Types of Validity

1. Statistical


2. Internal


3. Contruct


4. External/

Ways to help with V's and Z's

use equal sample size


measure better


increase strength of treatment


Increase variability


Switch Subject

Mautration

some event (naturally occuring that affects the experiment

Instrumentation

the masure device wears

Conflation

mixed effect of one factor with another

Three different spheres of research

Accounting


Auditing


Professional Structure

Improving One group pretestand posttest design

Double Pretest - add anotherpretest before the first one to understand any fluctuations before treatment isconsideredNonequivalent DependentVariable – Having a second variable that shouldn’t be affected by the treatmentbut measures similarly the experiment’s dependent variable (ex. toys advertisedaround Christmas time vs. Toys that are not)

Ancova

Analysis of covariance look at the projection of the points parrelell on the line on the y axis ( use when their is no overlapping

Anova

analysis of variance (just project to the y axis and look at the distribution based on that (can use when their is alot of overlap with V values)

Improving Quasi- Experimental Design w/o pretest (3 ways)

Independent Pretest Sample- draw from a random group from both the control and the testgroup (cross section) this is used when they think the prestest may have anaffect.Proxy Pretest –use a proxy to measure what the V’s and Z’s would have been (ex. algebra finalgrades if measuring effects of a calculus class)Matching or Stratifying – Example – using twins in a study

Types of Matching

Index


Cluster


Benchmark


Optimal

Index

Index Matching-selects multiple control units above and below a treatment unit

Cluster Group

- used to embed the treatment group in a cluster of similar control units

Benchmark Group matching

– selects control units that fall close to the treatment unit on a multivariate distance measure. Studies indicate that cluster and benchmark are better than index

Optimal matching

- each treatment unit may have multiple matched controls and vice versa

Problems with Matching

Selection Bias– you are picking the control groupsUndermatching –not finding the predictors of the outcomeIn general matching -may create an answer that doesn’t actually exists.

Principles to bettermatching

(1) Select groups that are assimilar as possible before matching and look at overlapping sections(2) Use matching variables that are stable and reliable (if theycorrelate with the outcome) [Stable Matched Bracketing]

Four threats too Quasi- Experimental Design w both control group/pretests

Selection Maturation


Selection-instrument threat


Selection-regression-(described in last reading)Selection-history –

Selection Maturation

– may arise if respondents in one group are growing more experienced, tired, or bored than respondents in another group

Selection-instrument threat

– nonequivalent groups begin at different points on the pretest. They are more accurate (1) the greater the initial nonequvalence between groups, (2) the greater the pretest posttest change, and (3) the closer any group means are to one end of the scale, so that a ceiling or floor exits.

Selection-history

– the possibility that an event occurred between pretest and posttest that affected one group more than another

Five Outcome Patterns

1. Both groups grow apart in the same direction – ( maturation)


2. No Change in the Control Group – Could dissect the data based on other Z’s or V’s but in generalyou can’t rely on the trend


3. Initial Pretest Difference Favoring the Treatment Group thatDiminish Over Time- Less likely due tomaturation


4. Initial Pretest Differences Favoring the Control Group thatDiminish Over Time – Subject to scaling(selection-instrumentation) and local threats (selection-history) probably notselection maturation


5. Outcomes that Cross Over in the Direction of Relationshipsregression risk,selection-instrument threat and selection maturation is less likely (harder toconclude; should get stronger design controls)

Elements of Design

1. Assignment


2. Measurement


3. Comparison Groups


4. Treatments