In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.

In a web-based experiment with 1,750 randomly sampled university students, we investigated the effect of mailed prenotification plus prepaid cash, mailed prenotification plus a prepaid voucher, mailed prenotification plus a postpaid voucher, and mailed prenotification on its own as compared to a control group without prenotification or incentives. Dependent measures were response, retention, and item nonresponse. Mailed prenotification over no prenotification increased response and retention and decreased item nonresponse. Prenotification plus prepaid cash maximized response and retention. Item nonresponse was lowest with prenotification plus postpaid vouchers and second lowest with prenotification plus prepaid cash. In addition, we compared the cost for all experimental groups. Total costs were highest for prenotification plus prepaid cash, but costs per respondent or per retainee were highest in the control group. In sum, this experiment shows ways of improving participation in web surveys.