Impacts of Food Hypersensitivities on Quality of Life in the UK and Willingness to Pay (WTP) to remove those impacts
Appendix P. Contingent Valuation Results: Adults
After respondents had completed the Discrete Choice Experiment, they were asked two open ended Contingent Valuation Method (CVM) questions.
First, they were asked what is the most they would be willing and able to pay to remove their FHS for a temporary period. They were randomly assigned a duration of 1 year, 3 years or 5 years.
They were then asked what is the most they would be willing and able to pay to remove their condition permanently.
Adult CVM Results: Temporary Removal
CVM Results: Temporary Removal in Aggregate
The mean WTP values for 1 year, 3 years or 5 years of removal for the pooled data are £696, £1678 and £2174 respectively, the median values are £100, £300 and £500 respectively – these median values correspond to a WTP value of £100/year.
Table 1. Summary statistics: Whole Sample by Removal Period
| Removal period | mean | sd | N | min | p25 | Median | p75 | Max |
|---|---|---|---|---|---|---|---|---|
| 1 year | 696.13 | 2559.23 | 424 | 0 | 0 | 100 | 500 | 40000 |
| 3 year | 1678.01 |
6230.84 |
423 | 0 | 5 | 300 | 1200 | 100000 |
| 5 year | 2173.51 | 4585.68 | 418 | 0 | 10 | 500 | 2500 | 50000 |
CVM Results: Temporary Removal by Condition
The mean WTP values for 1 year, 3 years or 5 years of removal for adults with a food allergy are £716, £1681, £2135 respectively, the median values are £100, £300 and £500 respectively – these median values correspond to a WTP value of £100/year.
Table 2. Summary statistics: Food Allergy by Removal Period
| Removal period | mean | sd | N | min | p25 | Median | p75 | Max |
|---|---|---|---|---|---|---|---|---|
| 1 year | 716.16 | 1869 | 117 | 0 | 0 | 100 | 500 | 15000 |
| 3 year | 1680.85 |
4266.34 |
109 | 0 | 1 | 300 | 1000 | 30000 |
| 5 year | 2135.45 | 4248.54 | 97 | 0 | 15 | 500 | 2500 | 30000 |
The mean WTP values for 1 year, 3 years or 5 years of removal for adults with coeliac disease are £682, £1713 and £2011 respectively, the median values are £100, £300 and £875 respectively.
Table 3. Summary statistics: Coeliac Disease by Removal Period
| Removal period | mean | sd | N | min | p25 | Median | p75 | Max |
|---|---|---|---|---|---|---|---|---|
| 1 year | 682.03 | 1919.42 | 179 | 0 | 0 | 100 | 500 | 15000 |
| 3 year | 1712.81 |
4814.34 |
183 | 0 | 0 | 300 | 1500 | 50000 |
| 5 year | 2011.41 | 3435.62 | 192 | 0 | 0 | 875 | 2500 | 25000 |
The mean WTP values for 1 year, 3 years or 5 years of removal for adults with a food intolerance are £698, £1627 and £2443, the median values are £100, £250 and £500 respectively.
Table 4. Summary statistics: Food Intolerance by Removal Period
| Removal period | mean | sd | N | min | p25 | Median | p75 | Max |
|---|---|---|---|---|---|---|---|---|
| 1 year | 697.53 | 3668.8 | 128 | 0 | .5 | 100 | 250 | 40000 |
| 3 year | 1627.04 | 8857.31 | 131 | 0 | 50 | 250 | 1000 | 100000 |
| 5 year | 2443.41 | 6102.64 | 129 | 0 | 30 | 500 | 2000 | 50000 |
The relationship between the mean WTP and the removal period is monotonic, with evidence of declining value of additional years (annual value is lower for 3 or 5 years of removal, than for 1 year).
Table 5. CVM WTP Values, in aggregate and by Condition
| Value | years | Mean, £ | /year | years | Median, £ | /year |
|---|---|---|---|---|---|---|
| Aggregate | 1 | 696 | 696 | 1 | 100 | 100 |
| Aggregate | 3 | 1678 | 559 | 3 | 300 | 100 |
| Aggregate | 5 | 2174 | 435 | 5 | 500 | 100 |
| Allergy | 1 | 716 | 716 | 1 | 100 | 100 |
| Allergy | 3 | 1681 | 560 | 3 | 300 | 100 |
| Allergy | 5 | 2135 | 427 | 5 | 500 | 100 |
| Coeliac | 1 | 682 | 682 | 1 | 100 | 100 |
| Coeliac | 3 | 1713 | 571 | 3 | 300 | 100 |
| Coeliac | 5 | 2011 | 402 | 5 | 875 | 175 |
| Intolerance | 1 | 698 | 698 | 1 | 100 | 100 |
| Intolerance | 3 | 1627 | 542 | 3 | 250 | 83 |
| Intolerance | 5 | 2443 | 489 | 5 | 500 | 100 |
Figure 1 Distribution of open ended WTP by period: adults
CVM Results: Permanent Removal
The mean WTP value for permanent removal for the pooled data was £5367, the median value was £1000.
Table 6. What is the most you are willing to pay for permanent removal of your condition?
| - | mean | std. Dev | N | Min | p25 | Median | p75 | max |
|---|---|---|---|---|---|---|---|---|
| Maximum WTP | 5366.8 | 11203.133 | 299 | 0 | 300 | 1000 | 5000 | 100000 |
The mean WTP value for permanent removal of food allergy, coeliac disease and food intolerance conditions are £6184, £6996 and £4054 respectively.
Table 7. What is the most you are willing to pay for permanent removal of your condition? By Only or Worst Condition
| Only or worst condition | mean | sd | N | min | p25 | Median | p75 | max |
|---|---|---|---|---|---|---|---|---|
| Food allergy | 6183.7 | 13166.96 | 366 | 0 | 70 | 5000 | 5000 | 100000 |
| Coeliac disease | 6996.3 | 14326.14 | 584 | 0 | 500 | 2500 | 7000 | 100000 |
| Food intolerance | 4054.3 | 9796.37 | 419 | 0 | 100 | 1000 | 5000 | 100000 |