2.2. Main study
Sample
Questionnaires were sent to households in each of three credit categories
within the area supplied by the collaborating utility company, Dffr
Cymru Welsh Water. Their supply area consisted of the whole of Wales
plus part of the county of Hereford and Worcester in England
The three credit status groups were:
Non-debtors: those who had had no outstanding debt to the company
within the past two years;
Mild debtors: those to whom a "final demand" (a second request for
payment following the normal bill) had been sent at least once within the
past two years, but who had paid their bill on receiving the final demand,
without further action by the company;
Serious debtors: those against whom court proceedings for recovery of
debt had been initiated within the past two years.
Four samples of about 1000 were drawn at random by Welsh Water staff
from the names and addresses of their customers, one each of Non-debtors
and Mild debtors, and two of Serious debtors. Envelope labels for these
customers were printed by Welsh Water and supplied to us. To protect
confidentiality, the credit categories were identified only by codes. We
selected 800 labels for each code at random, rejecting addresses outside the
Welsh Water area, presumably those of absentee landlords. Different
coloured questionnaires were sent to addresses bearing each code. In all,
therefore, 3200 questionnaires were mailed out, 800 each to non-debtors
and mild debtors, and 1600 to serious debtors. This represents about 0.32%
of all households in the Welsh Water area and, in order of magnitude
terms, about 0.1% of non-debtors, 1% of mild debtors and 10% of serious
debtors.
After all questionnaires had been mailed out, surplus labels were shredded,
and Welsh Water then informed us which credit categories corresponded
to each code. As an added measure to ensure confidentiality,
none of those handling the questionnaires had any substantial current
connection with Wales, and in fact none of us recognised any of the names
or addresses used.