Lec 5 1
What units are we measuring?
Each row corresponds to a unit in the study.
The first column identifies which unit.
The remaining columns represent variables.
Each variable describes a property of the units.
So what’s the unit here? The rows!
In this case the unit is “individuals.” Each row corresponds to one individual.
If we observed the data at this level, this is the unit of observation.
If we analyze the data at this level, this is the unit of analysis.
Beware the Ecological Fallacy!
Finding: In towns with higher religiosity levels, cohabitating is less common
Conclusion: Religious people are less likely to cohabit than non‐religious people.
Finding: In occupations with high levels of unionization, salaries are higher.
Conclusion: Workers in unions earn more than non‐unionized workers
Precision: fineness of distinctions made between attributes composing a variable
What does 8 years old really mean?
What does 2 years ago really mean?
What does 5.2 km from here really mean?
Accuracy: how reflective is a measure of the actual attribute of a variable
Whether a particular measurement yields the same results when applied repeatedly to
the same object/person
extent to which an empirical measure adequately reflects the agreed‐upon meaning of
Indices and scales
Indices: a composite measure created based on multiple items or indicators.
An index is constructed as a simple sum of effects or values through accumulatio
n of scores or numbers. It is a sum of concepts.
A scale is constructed by assigning scores to a range of intensities of response. Is
a measure of intensity of a single concept.
Scales tend to assume that when you have done the most intense aspect, you have
done the least as well. Lec 5 2
Index:Add all the responses
Scale: Count the “strongest”measure