SUTVA:
Stable Unit Treatment Values
Assumption. -1- No interference & -2- No hidden variations of treatment. The potential outcomes for any unit do not vary with the treatments assigned to other units.
How do you test Sutva?
test for SUTVA violations by
randomly varying the intensity of a randomly assigned treatment
. This double randomization allows first to estimate the impact of their treatment, which consists of a loan at harvest time, and then to estimate the impact of treatment spillovers.
What is the Sutva assumption?
Stable unit treatment value assumption (SUTVA)
We
require that “the [potential outcome] observation on one unit should be unaffected by the particular assignment of treatments to the other units
” (Cox 1958, §2.4). … We can account for dependent observations by considering more treatments.
Which of the following would be a violation of Sutva?
SUTVA is violated if
the random assignment of the individual to the same treatment condition at the same moment in time could result
in different outcomes.
What is Unconfoundedness assumption?
The unconfoundedness assumption says
loosely that all the variables affecting both the treatment T and the outcome Y are observed (we call them covariates)
and can be controlled for. … Abadie [5] and Frölich [6] extended these results to the situation where the observed covariates are related to the instrument.
Is there a causal effect?
Therefore, causal effect means that
something has happened
, or is happening, based on something that has occurred or is occurring. A simple way to remember the meaning of causal effect is: B happened because of A, and the outcome of B is strong or weak depending how much of or how well A worked.
What is the problem with causal inference?
The fundamental problem for causal inference is that, for any individual unit, we can observe only one of Y(1) or Y(0), as indicated by W; that is, we
observe the value of the potential outcome under only one of the possible treatments
, namely the treatment actually assigned, and the potential outcome under the other …
What is a difference in difference analysis?
The difference-in-differences method is a
quasi-experimental approach that compares the changes in outcomes over time between a population enrolled in a program
(the treatment group) and a population that is not (the comparison group). It is a useful tool for data analysis.
What is causal inference in statistics?
Causal inference is
the process of determining the independent, actual effect of a particular phenomenon that is a component of a larger system
. … Causal inference is said to provide the evidence of causality theorized by causal reasoning. Causal inference is widely studied across all sciences.
What is strong Ignorability?
Strong ignorability is
about potential outcomes
(the pretreatment covariates that act as two separate combinations of X), not about the observed outcomes.
What are parallel trends assumptions?
The parallel trends assumption states that, although treatment and comparison groups may have different levels of the outcome prior to the start of treatment,
their trends in pre-treatment outcomes should be the same
.
What is inverse probability weighting treatment?
The inverse probability of treatment weight is defined as
w = Z e + 1 − Z 1 − e
. Each subject’s weight is equal to the inverse of the probability of receiving the treatment that the subject received 4.
What is propensity matched analysis?
In the statistical analysis of observational data, propensity score matching (PSM) is
a statistical matching technique that attempts to estimate the effect of a treatment, policy, or other intervention by accounting for the covariates that predict receiving the treatment
.
How does propensity score matching work?
Propensity score matching (PSM) is a
quasi-experimental method in which the researcher uses statistical techniques to construct an artificial control group by matching each treated unit with a non-treated unit of similar characteristics
. Using these matches, the researcher can estimate the impact of an intervention.
How do you show causal effect?
To establish causality you need to show three things–
that X came before Y
, that the observed relationship between X and Y didn’t happen by chance alone, and that there is nothing else that accounts for the X -> Y relationship.
Can causality be proven?
In order to prove causation we need
a randomised experiment
. We need to make random any possible factor that could be associated, and thus cause or contribute to the effect. … If we do have a randomised experiment, we can prove causation.
