Fig. 1
The effects of external and internal reference prices on estimated PWYW measured for unknown quality of the e-book.
Tab. 1
The average of estimated PWYW payments for e-books with perceived low, unknown and high quality – results in PLN presented separately for treatments with different external reference prices and the control group without the external reference price
| Low quality | Unknown quality | High quality | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | |
| Min | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 8 | 1 | 1 | 5 | 15 |
| Max | 36.7 | 10 | 20 | 29 | 36.7 | 15 | 20 | 30 | 50 | 20 | 25 | 39.9 |
| Mean | 8.902 | 4.115 | 8.476 | 11.481 | 14.151 | 6.449 | 12.361 | 17.736 | 21.260 | 9.065 | 17.310 | 25.703 |
| p-value(1) | 0.000 | 0.309 | 0.996 | 0.000 | 0.013 | 1.000 | 0.000 | 0.000 | 1.000 | |||
| p-value(2) | 0.000 | 0.807 | 0.048 | 0.000 | 0.127 | 0.000 | 0.000 | 0.000 | 0.001 | |||
| p-value(3) | 0.000 | 0.977 | 0.003 | 0.000 | 0.157 | 0.000 | 0.000 | 0.000 | 0.000 | |||
| Standard deviation | 5.972 | 3.168 | 4.551 | 6.046 | 6.032 | 2.738 | 3.5125 | 5.188 | 8.497 | 2.733 | 3.314 | 5.941 |
| Observations | 77 | 78 | 78 | 84 | 77 | 78 | 78 | 84 | 77 | 78 | 78 | 84 |
[i] (1) Ha: mean from control group > mean from treatment 9.90, 19.90 and 39.90, respectively. Two-sample t-test on the equality of means.
(2) Ha: independent samples in control group and in treatment 9.90, 19.90 and 39.90, respectively, were drawn from populations with the same median. Nonparametric two-sample test on the equality of medians with unmatched data.
(3) Ha: independent samples in control group and in treatment 9.90, 19.90 and 39.90, respectively, are from populations with the same distribution. Wilcoxon rank-sum (Mann-Whitney) test.
Tab. 2
The average of estimated PWYW payments for e-books with perceived low, unknown and high quality - results in PLN presented separately for all treatments and the control group, and different levels of individual internal reference prices
| Low quality | Unknown quality | High quality | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | ||
| Internal reference price between <9.90,19.90) | 7.54 | 3.48 | 8.73 | 11.61 | 11.95 | 5.85 | 11.72 | 18.05 | 17.50 | 8.29 | 16.38 | 24.66 | |
| p-value(1) | 0.001 | 0.000 | 0.000 | - | |||||||||
| Observations with internal reference price < 19.90, 39.90) | 22 | 24 | 15 | 18 | 22 | 24 | 15 | 18 | 22 | 24 | 15 | 18 | - |
| Internal reference price between < 19.90, 39.90) | 14.34 | 5.86 | 11.22 | 12.55 | 19.7 | 8.61 | 14.40 | 18.43 | 27.82 | 10.78 | 18.89 | 27.48 | - |
| p-value(1) | 0.186 | 0.050 | 0.014 | - | |||||||||
| Observations with internal reference price < 19.90, 39.90) | 11 | 16 | 12 | 16 | 11 | 16 | 12 | 16 | 11 | 16 | 12 | 16 | - |
| Observations with revealed internal reference prices* | 34 | 40 | 28 | 36 | 34 | 40 | 28 | 36 | 34 | 40 | 28 | 36 | - |
| All observations per treatment | 77 | 78 | 78 | 84 | 77 | 78 | 78 | 84 | 77 | 78 | 78 | 84 | - |
[i] Notes: All respondents received three vignettes (low, unknown, high quality), so the number of observations is the same in all quality-scenarios for control group and treatments with 00 respective external reference prices.
*Some respondents did not provide information on neither the price most recently paid for an e-book nor the average price they usually pay for e-books. Additionally, the extreme internal reference price intervals < 0, 9.90) and < 39.90, max) were omitted since we had only few observations that fit into these, and they might be considered outliers. Therefore, we could calculate individual reference prices for only 136 respondents, and divide them amongst all treatments.
(1) Ha: mean from control group > mean from treatment 9.90 and 19.90, respectively, for a given interval of internal reference price. Two-sample t-test on the equality of means.
Tab. 3
Results of random-effects GLS regression, with estimated PWYW payments as dependent variable, and internal reference price as an individual-specific independent variable
| Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | |
|---|---|---|---|---|
| Internal reference price | 0.535** | 0.182** | 0.217 | 0.388*** |
| (0.216) | (0.079) | (0.150) | (0.116) | |
| Author reward | 0.103** | 0.019 | 0.011 | 0.057 |
| (0.046) | (0.024) | (0.043) | (0.046) | |
| Publication costs | 0.112* | 0.035 | 0.050 | -0.055 |
| (0.061) | (0.028) | (0.046) | (0.065) | |
| Distribution costs | 0.009 | -0.017 | 0.002 | 0.026 |
| (0.068) | (0.027) | (0.057) | (0.051) | |
| Risk loving | 0.726 | 0.381* | -0.106 | 0.092 |
| (0.501) | (0.210) | (0.306) | (0.327) | |
| Age | 0.138 | -0.005 | -0.023 | -0.115 |
| (0.147) | (0.035) | (0.082) | (0.075) | |
| Sex | 3.396 | 2.772*** | 0.678 | 2.413 |
| (2.391) | (0.975) | (1.466) | (1.570) | |
| Unknown quality | 4.591*** | 2.520*** | 3.140*** | 6.114*** |
| (0.929) | (0.405) | (0.658) | (0.849) | |
| High quality | 10.806*** | 4.850*** | 7.669*** | 13.847*** |
| (0.929) | (0.405) | (0.658) | (0.849) | |
| Constant | -21.293*** | -5.634* | 4.203 | 4.227 |
| (7.670) | (3.037) | (4.454) | (5.012) | |
| Observations | 102 | 120 | 84 | 108 |
| Number of respondents | 34 | 40 | 28 | 36 |
[i] Standard errors in parentheses
*** p < 0.01, ** p < 0.05, * p < 0.1
Tab. 4
Results of random-effects GLS regression, with estimated PWYW payments as dependent variable, without internal reference price as independent variable
| Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | |
|---|---|---|---|---|
| Author reward | 0.108*** | 0.010 | 0.005 | 0.057* |
| (0.030) | (0.015) | (0.020) | (0.031) | |
| Publication costs | 0.104*** | 0.017 | 0.019 | 0.014 |
| (0.035) | (0.017) | (0.020) | (0.034) | |
| Distribution costs | 0.042 | -0.002 | -0.021 | 0.034 |
| (0.041) | (0.017) | (0.028) | (0.039) | |
| Risk loving | 0.851*** | 0.207 | 0.259 | 0.368* |
| (0.249) | (0.135) | (0.174) | (0.210) | |
| Age | -0.007 | 0.014 | -0.012 | -0.019 |
| (0.066) | (0.027) | (0.037) | (0.053) | |
| Sex | 2.999** | 1.190** | 1.074 | 1.410 |
| (1.309) | (0.568) | (0.711) | (1.054) | |
| Unknown quality | 5.248*** | 2.333*** | 3.871*** | 6.255*** |
| (0.622) | (0.287) | (0.459) | (0.586) | |
| High quality | 12.357*** | 4.950*** | 8.755*** | 14.222*** |
| (0.622) | (0.287) | (0.459) | (0.586) | |
| Constant | -6.807 | 0.021 | 5.632** | 5.508 |
| (4.218) | (1.764) | (2.229) | (3.846) | |
| Observations | 231 | 234 | 231 | 252 |
| Number of respondents | 77 | 78 | 77 | 84 |
[i] Standard errors in parentheses
*** p < 0.01, ** p < 0.05, * p < 0.1
Tab. 1
OLS regressions, with estimated PWYW payments as dependent variable. Regressions for e-book with low quality, estimated separately for each treatment and control group, with and without internal reference price as explanatory variable.
| With internal reference price | Without internal reference price | |||||||
|---|---|---|---|---|---|---|---|---|
| Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | |
| Publication costs | 0.187*** | 0.056 | 0.054 | -0.132* | 0.109*** | 0.037* | -0.000 | 0.010 |
| (0.051) | (0.036) | (0.065) | (0.076) | (0.032) | (0.021) | (0.030) | (0.044) | |
| Author reward | 0.110** | 0.052* | 0.023 | 0.051 | 0.089*** | 0.033* | -0.014 | 0.034 |
| (0.044) | (0.030) | (0.060) | (0.050) | (0.029) | (0.018) | (0.029) | (0.040) | |
| Risk loving | 0.624 | 0.328 | -0.343 | -0.217 | 0.901*** | 0.210 | -0.001 | 0.279 |
| (0.481) | (0.266) | (0.379) | (0.365) | (0.242) | (0.171) | (0.238) | (0.268) | |
| Internal reference price | 0.367* | 0.166 | 0.296 | 0.529*** | ||||
| (0.206) | (0.102) | (0.210) | (0.134) | |||||
| Age | 0.255* | -0.015 | -0.019 | -0.142 | 0.015 | -0.002 | 0.034 | -0.051 |
| (0.136) | (0.045) | (0.116) | (0.084) | (0.063) | (0.034) | (0.055) | (0.068) | |
| Sex | 3.419 | 2.022 | 0.350 | 2.277 | 2.265* | 0.472 | 1.700 | 0.255 |
| (2.210) | (1.198) | (2.055) | (1.780) | (1.262) | (0.712) | (1.068) | (1.363) | |
| Constant | -20.977*** | -3.451 | 4.315 | 9.759* | -3.261 | 0.916 | 6.826** | 10.824** |
| (6.124) | (3.265) | (5.790) | (5.327) | (3.261) | (1.951) | (2.936) | (4.274) | |
| Observations | 34 | 40 | 28 | 36 | 77 | 78 | 77 | 84 |
| R-squared | 0.609 | 0.240 | 0.145 | 0.415 | 0.309 | 0.104 | 0.044 | 0.042 |
[i] Standard errors in parentheses
*** p < 0.01, ** p < 0.05, * p < 0.1
Tab. 2
OLS regressions, with estimated PWYW payments as dependent variable. Regressions for e-book with unknown quality, estimated separately for each treatment and control group, with and without internal reference price as explanatory variable.
| With internal | reference | price | Without | internal reference | price | |||
|---|---|---|---|---|---|---|---|---|
| Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | |
| Publication costs | 0.126** | 0.025 | 0.042 | -0.103 | 0.115*** | 0.015 | 0.019 | -0.001 |
| (0.051) | (0.031) | (0.047) | (0.070) | (0.032) | (0.018) | (0.022) | (0.036) | |
| Author reward | 0.120** | 0.011 | 0.014 | 0.011 | 0.113*** | 0.010 | 0.018 | 0.037 |
| (0.045) | (0.026) | (0.043) | (0.046) | (0.030) | (0.016) | (0.022) | (0.033) | |
| Risk loving | 0.732 | 0.407* | 0.022 | 0.131 | 0.683*** | 0.221 | 0.288 | 0.567** |
| (0.484) | (0.228) | (0.274) | (0.334) | (0.246) | (0.146) | (0.181) | (0.221) | |
| Internal reference price | 0.472** | 0.178* | 0.166 | 0.396*** | ||||
| (0.208) | (0.087) | (0.152) | (0.123) | |||||
| Age | 0.124 | 0.038 | -0.018 | -0.125 | -0.027 | 0.040 | 0.021 | 0.008 |
| (0.137) | (0.039) | (0.084) | (0.077) | (0.064) | (0.029) | (0.042) | (0.056) | |
| Sex | 3.451 | 2.765** | 1.129 | 2.618 | 2.890** | 1.437** | 0.923 | 1.522 |
| (2.227) | (1.028) | (1.487) | (1.631) | (1.281) | (0.607) | (0.813) | (1.122) | |
| Constant | -12.434* | -2.045 | 8.092* | 16.063*** | 3.532 | 2.312 | 8.433*** | 12.665*** |
| (6.171) | (2.800) | (4.190) | (4.879) | (3.310) | (1.665) | (2.236) | (3.516) | |
| Observations | 34 | 40 | 28 | 36 | 77 | 78 | 77 | 84 |
| R-squared | 0.592 | 0.307 | 0.136 | 0.346 | 0.302 | 0.126 | 0.071 | 0.119 |
[i] Standard errors in parentheses
*** p < 0.01, ** p < 0.05, * p < 0.1
Tab. 3
OLS regressions, with estimated PWYW payments as dependent variable. Regressions for e-book with high quality, estimated separately for each treatment and control group, with and without internal reference price as explanatory variable.
| With internal reference price | Without internal reference price | |||||||
|---|---|---|---|---|---|---|---|---|
| Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | Control group | Low price treatment 9.90 | Medium price treatment 19.90 | High price treatment 39.90 | |
| Publication costs | 0.035 | 0.028 | 0.042 | 0.061 | 0.125** | 0.001 | 0.037* | 0.036 |
| (0.074) | (0.029) | (0.047) | (0.093) | (0.048) | (0.018) | (0.020) | (0.041) | |
| Author reward | 0.082 | -0.003 | 0.014 | 0.085 | 0.114** | -0.013 | 0.014 | 0.082** |
| (0.064) | (0.024) | (0.043) | (0.061) | (0.044) | (0.016) | (0.020) | (0.037) | |
| Risk loving | 0.848 | 0.329 | 0.022 | 0.512 | 1.011*** | 0.187 | 0.325* | 0.380 |
| (0.695) | (0.212) | (0.274) | (0.444) | (0.366) | (0.146) | (0.163) | (0.246) | |
| Internal reference price | 0.752** | 0.205** | 0.166 | 0.268 | ||||
| (0.298) | (0.081) | (0.152) | (0.163) | |||||
| Age | 0.017 | -0.028 | -0.018 | -0.110 | -0.050 | 0.002 | -0.076** | -0.039 |
| (0.196) | (0.036) | (0.084) | (0.102) | (0.095) | (0.029) | (0.038) | (0.062) | |
| Sex | 3.601 | 2.929*** | 1.129 | 2.921 | 4.432** | 1.638*** | 0.674 | 2.878** |
| (3.193) | (0.954) | (1.487) | (2.166) | (1.907) | (0.610) | (0.732) | (1.252) | |
| Constant | -4.123 | 2.974 | 8.092* | 16.319** | 8.790* | 7.582*** | 16.442*** | 20.595*** |
| (8.850) | (2.600) | (4.190) | (6.480) | (4.926) | (1.671) | (2.014) | (3.924) | |
| Observations | 34 | 40 | 28 | 36 | 77 | 78 | 77 | 84 |
| R-squared | 0.457 | 0.336 | 0.136 | 0.274 | 0.221 | 0.117 | 0.151 | 0.164 |
[i] Standard errors in parentheses
*** p < 0.01, ** p < 0.05, * p < 0.1