Table 1.
Results of alternative-specific multinomial probit regression analyses and WTP values
| Diarrhoea | Dizziness | Chest pain | ||
|---|---|---|---|---|
| Constant | Constant (β) | 0.031 | 0.4686b | 1.0552b |
| WTP (95% CI) | n/s | £25.12 (£18.76 to £31.47) | £160.47 (£111.06 to £209.9) | |
|
| ||||
| Action you take | Self-care (β)a | 0.6811b | −0.0994b | −0.4807b |
| WTP (95% CI) | £32.61 (£27.62 to £37.61) | −£5.33 (−£10.03 to £0.63) | −£73.11 (−£86.95 to −£59.26) | |
|
| ||||
| NHS 24/NHS Direct (β) | −0.1620b | 0.0017 | 0.0610b | |
| WTP (95% CI) | −£7.76 (−£12.09 to −£3.42) | n/s | £9.27 (£0.47 to £18.07) | |
|
| ||||
| Nurse (β) | −0.0367 | 0.3381b | 0.2779b | |
| WTP (95% CI) | n/s | £18.12 (£13.04 to £23.20) | £42.26 (£31.24 to £53.28) | |
|
| ||||
| Pharmacist (β) | 0.2922b | −0.0007 | −0.0943b | |
| WTP (95% CI) | £13.99 (£9.51 to £18.48) | n/s | −£14.34 (−£24.33 to −£4.35) | |
|
| ||||
| Complementary practitioner (β) | −0.6799b | −0.648b | −0.3012b | |
| WTP (95% CI) | −£32.56 (−£37.90 to −£27.21) | −£34.73 (−£40.12 to −£29.34) | −£45.8 (−£57.22 to −£34.38) | |
|
| ||||
| GP (β) | −0.0948b | 0.4084b | 0.5374b | |
| WTP (95% CI) | −£4.54 (−£8.94 to −£0.14) | £21.89 (£17.32 to £26.45) | £81.72 (£66.54 to £96.91) | |
|
| ||||
| Waiting time | 0 hours (β)a | 0.4620b | 0.3905b | 0.3799b |
| WTP/hour (95% CI) | £22.13 (£16.71 to £27.54) | £20.93 (£15.20 to £26.66) | £57.76 (£43.86 to £71.67) | |
|
| ||||
| 1 hour (β) | 0.3530b | 0.3996b | 0.4123b | |
| WTP/hour (95% CI) | £16.90 (£12.74 to £21.06) | £21.42 (£17.15 to £25.68) | £62.71 (£50.77 to £74.64) | |
|
| ||||
| 6 hours (β) | 0.1686b | 0.2153b | 0.3020b | |
| WTP/hour (95% CI) | £8.07 (£4.17 to £11.98) | £11.54 (£7.47 to £15.61) | £45.91 (£35.28 to £56.54) | |
|
| ||||
| 1 day/24 hours (β) | 0.2332b | 0.3155b | 0.2077b | |
| WTP/hour (95% CI) | £11.17 (£7.03 to £15.30) | £16.91 (£12.48 to £21.34) | £31.58 (£21.89 to £41.27) | |
|
| ||||
| 3 days/72 hours (β) | −0.1721b | −0.2619b | −0.3407b | |
| WTP/hour (95% CI) | −£8.24 (−£13.04 to −£3.44) | −£14.04 (−£18.88 to −£9.19) | −£51.81(−£63.82 to −£39.79) | |
|
| ||||
| 8 days/192 hours (β) | −1.0447b | −1.0589b | −0.9611b | |
| WTP/hour (95% CI) | −£50.03 (−£56.62 to −£43.44) | −£56.75 (−£63.38 to −£50.14) | −£146.16 (−£170.1 to −£122.22) | |
|
| ||||
| Time available for consultation | Minutes, (β) | −0.0001 | 0.0006 | −0.0005 |
| WTP/minute (95% CI) | n/s | n/s | n/s | |
|
| ||||
| Convenience/availability | Working hours only (β)a | −0.0292 | −0.0496b | −0.0193b |
| WTP (95% CI) | n/s | −£2.66 (−£4.39 to £0.92) | −£2.94 (−£6.26 to £0.37) | |
|
| ||||
| Any time (β) | 0.0292 | 0.0496b | 0.0193b | |
| WTP (95% CI) | n/s | £2.66 (£0.92 to £4.39) | £2.94 (−£0.37 to £6.26) | |
|
| ||||
| Chance of a satisfactory outcome | Poor (β)a | −0.8612b | −0.9646b | −0.6448b |
| WTP (95% CI) | −£41.24 (−£45.62 to −£36.86) | −£51.70 (−£56.54 to −£46.86) | −£98.06 (−£114.09 to −£82.03) | |
|
| ||||
| Fair (β) | −0.2389b | −0.2075b | −0.0814b | |
| WTP (95% CI) | −£11.44 (−£14.14 to −£8.74) | −£11.12 (−£13.81 to −£8.43) | −£12.38 (−£18.81 to −£5.96) | |
|
| ||||
| Good (β) | 0.3867b | 0.5421b | 0.2763b | |
| WTP (95% CI) | £18.51 (£15.77 to £21.26) | £29.06 (£25.45 to £32.67) | £42.01 (£32.83 to £51.19) | |
|
| ||||
| Very good (β) | 0.7134b | 0.6299b | 0.4500b | |
| WTP (95% CI) | £34.16 (£30.61 to £37.72) | £33.77 (£29.78 to £37.75) | £68.43 (£56.35 to £80.51) | |
|
| ||||
| Cost | Cost (β) | −0.0209b | −0.0187b | −0.0066b |
| 95% CI | −0.0228 to −0.0189 | −0.0206 to −0.0167 | −0.0079 to −0.0052 | |
| P-value | <0.001 | <0.001 | <0.001 | |
|
| ||||
| Log likelihood | −5209.892 | −4877.9286 | −4229.0126 | |
|
| ||||
| Number of individuals (observations) | 795 (18 417) | 797 (18 507) | 793 (18 450) | |
n/s = not significant. WTP = willingness to pay. Effects coding was used for ‘action you take’, ‘convenience/availability’, ‘chance of a satisfactory outcome’, and ‘waiting time’. ‘Consultation time’ and ‘cost’ were modelled as continuous variables.
a
Using effects coding L-1 levels are calculated using the regression model, the missing level is obtained from the negative of the sum of all other coefficients.
b
Significant at the 5% level.