Explanation 4
Variation in Response Functions
Basic assumption of Survey Research:
Equality of the response function
People express themselves in
different ways
Expression of Kissinger
Translation by Israeli
• Suicidal
• Difficult to obtain
• Impossible
• Unlikely
• Difficult to get
• Achievable
• I will see what I can do
• I got this concession a
long time ago
The problem of Variation in Response
Function (VRF)
• Large differences in the way
the respondents express
themselves
• Differences eventhough
they have the same opinion
• The answers don´t indicate
the same opinion
• These effects are systematic
• The consequence of VRF is
correlation between items
eventough the respondents
have the same opinions
Can this be observed?
• How qualified is a person for his job if (s)he has x
years experience where x = 1,2,3,6,10,15,20
Evaluation of sizes of squares
Judgment of length of lines in numbers
at two occasions by 9 persons
Do the coefficients have substantive
importance?
• In substantive judgments the slope can indicate
How the respondents judges different objects
• We ask people to evaluate
How serious is the polution of x square meters of
soil?
How serious is the dealth of x birds by polution ?
How large is the number x
x has different but the same values in all three
experiments
All judgments have been expressed in length of lines
The meaning of the regression
coefficients
We also asked
• How threatening 12 environmental catastrophies
are? (4 categories)
The items form a Mokken scale
• What is the most serious problem nowadays?
We use the rank number of enviromental problems
as an indicator of environmental conscienceness.
The correlations of the slope coefficients
with the other scale scores
Conclusion
• VRF has been observed in very simple
judgments tasks
• So it is very likely that it also occurs in more
difficult judgments tasks like attitude scales
• There it is difficult to show because
difference of opinion and difference in
response function can normally not be
separated
Correction for VRF
• If this is the situation the respondents differ in
• Individual intercept and slope
• Individual means and standard deviation
Experiment
• How threatening are the
following phenomena for the
eviroment ?
The observed corrections
Correction for the individual
standard deviations
Correction for individual Means and
standard deviations
What to do?
• Correction for the standard deviations leads
to very high correlations between the items
• Correction for the means and the standard
deviations leads to very minimal correlations
between the items
• Correction can take away a part of the
difference in opinion or leave some
difference because of VRF
Alternative: Prevent VRF using fixed
reference points
This means that we expect different coefficients
between the respondents for instructions without a
fixed reference point or one fixed reference point
but not if two fixed reference points are specified
The results of the test
Formulation of ESS questions with fixed
reference points
There is only one linear response function
possible but people can express different
opinions
Response
10
0
No trust
at all
resp1
resp2
resp3
Complete
trust
Opinion
Conclusions
• VRF is an alternative explanation for simplex
type correlation matrices for attitude items
• Corrections for VRF seems not possible after
the data are collected because one can
also take away a part of the difference in
opinions between people
• One can better prevent VRF by use of fixed
reference points on the scales
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