Most of us Monitoring &
Evaluation (M&E) professionals are acquainted with the problem of
attribution.
The attribution
problem is often referred to as the central problem in impact evaluation. The central
question is to what extent changes in outcomes of interest can be attributed
to a particular intervention.
Attribution refers
to both isolating and estimating accurately the particular contribution of an
intervention and ensuring that causality runs from the intervention to the outcome.
So how do we
establish impact? Most of the time, it is with comparison with the baseline. Baseline data (before the intervention)
and end-line data (after the intervention)
give facts about the development over time and describe “the factual” for the treatment
group (not the counterfactual).
But changes observed
by comparing before-after (or pre-post) data are rarely caused by the
intervention alone, as other interventions and processes influence
developments, both in time and space. Additional tasks of tracing impact back
from interventions to specific (financial) contributions of different donors,
are meaningless though this is what many terms of references require us to do.
Three
related are problems are
1) establishment of a counter-factual;
2) elimination of
selection effects and
3) problem of unobservables.
Though we often
could choose one among several methods - quantitative; experimental and/or
quasi-experimental methods, many of these limitations remain or are compounded by
using a combination of these methods.
So while M&E professionals
frequently undertake often profitable impact evaluation studies, most of us do
not take seriously our own findings.
Similar is the
situation with climate change. While science illiterate NGO activists at the
top of their hats attribute every extreme event to climate change; so far
climatologists have not been able to establish it by hard scientific evidence.
A new paper in Nature this week goes
right to the heart of the conversation about extreme events and their potential
relationship to climate change. This is a complex issue and one not well-suited
to sound bite quotes and headlines and so we give a gist of it here:
- Not all extremes are the same. Discussions of ‘changes in
extremes’ in general without specifying exactly what is being discussed
are meaningless. A tornado is an extreme event, but one whose causes,
sensitivity to change and impacts have nothing to do with those related to
an ice storm, or a heat wave or cold air outbreak or a drought.
- There is no theory or result that indicates
that climate change increases extremes in general. This is a corollary of the
previous statement – each kind of extreme needs to be looked at
specifically – and often regionally as well.
- Some extremes will become more common in
future (and some less so). We will discuss the specifics below.
- Attribution of extremes is hard. There are limited
observational data to start with, insufficient testing of climate model
simulations of extremes, and (so far) limited assessment of model
projections.
In short the paper
concluded that attribution is a central problem and better models are needed
before exceptional events can be reliably linked to global warming.
To read the full
Nature paper on Extreme Events, Click here
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