Table 3.
Experimental design information DCEs
| Item | Category | 1990–2000 | 2001–2008 | 2009–2012 | Current: 2013–2017 | ||||
|---|---|---|---|---|---|---|---|---|---|
| N = 34a | (%)b | N = 114a | (%)b | N = 179a | (%)b | N = 301a | (%)b | ||
| Design type | Full factorial | 4 | (12) | 0 | (0) | 9 | (5) | 13 | (4) |
| Fractional | 25 | (74) | 114 | (100) | 158 | (88) | 269 | (89) | |
| Not clearly reported | 5 | (15) | 0 | (0) | 12 | (7) | 19 | (6) | |
| Design plan | Main effects only | 25 | (74) | 100 | (89) | 98 | (55) | 86 | (29) |
| Main effects and two-way interactions | 2 | (6) | 6 | (5) | 23 | (13) | 52 | (17) | |
| Not applicable | 4 | (12) | 0 | (0) | 5 | (3) | 5 | (2) | |
| Other | N/C | N/C | N/C | N/C | N/C | N/C | 11 | (4) | |
| Not clearly reported | 3 | (9) | 8 | (7) | 52 | (29) | 147 | (49) | |
| Blocking | Yes | N/C | N/C | N/C | N/C | N/C | N/C | 150 | (50) |
| No | N/C | N/C | N/C | N/C | N/C | N/C | 60 | (20) | |
| Not clearly reported | N/C | N/C | N/C | N/C | N/C | N/C | 91 | (30) | |
| Design software | Ngene | N/C | N/C | N/C | N/C | N/C | N/C | 62 | (21) |
| SAS | 0 | (0) | 14 | (12) | 41 | (23) | 54 | (18) | |
| Sawtooth | 2 | (6) | 5 | (4) | 30 | (17) | 47 | (16) | |
| SPEED | 13 | (38) | 22 | (19) | 9 | (5) | 1 | (0) | |
| SPSS | 2 | (6) | 14 | (12) | 13 | (7) | 20 | (7) | |
| Not applicable | N/C | N/C | N/C | N/C | N/C | N/C | 11 | (3) | |
| Other | 2 | (6) | N/C | N/C | 27 | (15) | 7 | (2) | |
| Not clearly reported | N/C | N/C | 4 | (4) | 9 | (5) | 99 | (33) | |
| Design source | Website | 0 | (0) | 3 | (3) | 9 | (5) | 4 | (1) |
| Expert | 4 | (12) | 4 | (4) | 11 | (6) | 5 | (2) | |
| Not clearly reported | 9 | (26) | 42 | (37) | 30 | (17) | 215 | (71) | |
| Methods to create choice sets | Orthogonal: single profiles (binary choices) | 3 | (9) | 12 | (11) | 2 | (1) | 7 | (2) |
| Orthogonal: random pairing | 18 | (53) | 19 | (17) | 18 | (10) | 12 | (4) | |
| Orthogonal: pairing with constant comparator | 6 | (18) | 23 | (20) | 5 | (3) | 0 | (0) | |
| Orthogonal: foldover-random pairing | 0 | (0) | 1 | (1) | 4 | (2) | 2 | (1) | |
| Orthogonal: foldover | 0 | (0) | 11 | (10) | 34 | (19) | 26 | (9) | |
| D-efficiency | 0 | (0) | 14 | (12) | 54 | (30) | 105 | (35) | |
| Bayesian D-efficiency | N/C | N/C | N/C | N/C | N/C | N/C | 23 | (8) | |
| Other | 4 | (12) | 2 | (2) | 27 | (15) | 26 | (9) | |
| Not clearly reported | 3 | (9) | 32 | (28) | 39 | (22) | 100 | (33) | |
DCE discrete choice experiment, N/C not collected (data were not collected for this specific category)
aNumbers of individual studies might not add up to total Ns as some studies addressed multiple topics
bPercentages might not add up to 100% because some studies addressed multiple topics and because of rounding error