Trade-off Between Data Collection Methods, Bias and Costs
||Can be high with call-backs.
Needs pre-information and publicity to improve involvement.
Contact rate can then be c70%
||Can be Low
||Can be high, using call-backs
and pre-information helps contact rate.
likely to be high (given reducing use of land-lines, TPS etc.
Some response bias likely
||Response rates seem to be
declining (40% is a good rate at present)
||Response bias can
be high. Certain groups less likely to respond.
||Response is usually fairly
low (less than half of postal). Incentives can increase
||Usually high –
from selection bias and response bias.