| |
Cost
|
Incentive
|
No incentive
|
|
Randomised
| |
1070
|
1074
|
|
Initial mailing (printing, envelope, postage)
|
£1.25
|
1070
|
1074
|
|
Incentive
|
£5
|
1070
|
0
|
|
Repeat copy of mailing (printing, envelope, postage)
|
£1.25
|
504
|
577
|
|
First follow-up phone call
|
£0.90
|
808
|
844
|
|
Second follow-up phone call
|
£0.90
|
497
|
578
|
|
Telephone data collection – unsuccessful
|
£1.09
|
396
|
472
|
|
Telephone data collection – successful
|
£6.54
|
101
|
115
|
|
Questionnaire returned
|
£0.52
|
810
|
738
|
|
Cost per participant randomised
| |
£9.35
|
£4.64
|
|
Cost per questionnaire returned
| |
£12.35
|
£6.76
|
