choice-metrics.com

Dear Ngene users,
I have run the following syntax (conditional design) and received the following "Ngene has stopped working"
When I remove the ;alg=mfederov command, the program is running but the results do not meet the conditiona (i.e. engagement types do not appear with the correct price levels) any ideas what might be the reason? Anat

Design
;alts = small,optout
;rows=24
;block=6
;eff=(mnl,d)
;rdraws=halton
;alg=mfederov
;reject:

small.engagement=1 and small.cost=8,
small.engagement=1 and small.cost=13,
small.engagement=1 and small.cost=18,
small.engagement=1 and small.cost=40,
small.engagement=1 and small.cost=55,
small.engagement=1 and small.cost=75,

small.engagement=2 and small.cost=70,
small.engagement=2 and small.cost=120,
small.engagement=2 and small.cost=150,
small.engagement=2 and small.cost=40,
small.engagement=2 and small.cost=55,
small.engagement=2 and small.cost=75,

small.engagement=3 and small.cost=70,
small.engagement=3 and small.cost=120,
small.engagement=3 and small.cost=150,
small.engagement=3 and small.cost=8,
small.engagement=3 and small.cost=13,
small.engagement=3 and small.cost=18

;model:
U(small) = c2[0] + b1.dummy[(n, 2.8, 0.21)|(n,1.6, 0.4)]*engagement[1,2,3] +
b2[(n,-0.008,0.0004)]*cost[8,13,18,40,55,70,75,120,150](1-3,1-3,1-3,1-3,1-3,1-3,1-3,1-3,1-3)+b3.dummy[(n,-0.22,0.00017)]*nolocal[1,0] $

The reason is that you ask for 24 rows, whereas there only exist 18 rows that satisfy your constraints:

Choice situation , small.engagement, small.cost, small.nolocal
1 1 70 1
2 1 70 0
3 1 120 1
4 1 120 0
5 1 150 1
6 1 150 0
7 2 8 1
8 2 8 0
9 2 13 1
10 2 13 0
11 2 18 1
12 2 18 0
13 3 40 1
14 3 40 0
15 3 55 1
16 3 55 0
17 3 75 1
18 3 75 0

Hence, the design you are looking for does not exist. You either have to decrease the number of choice tasks to 18 or lower, or to remove some constraints.

I would suggest that you install Ngene version 1.1.2, as then you would have received the following error message:
"[Modified Federov] ERROR: The candidate set of the Modified Federov algorithm is smaller than the number of rows specified. That is, there are not enough unique choice sets to generate the number required as specificed in the ;rows property. This problem sometimes appears when there are too many reject and/or reject constraints."

Thank you Michiel.. that was indeed the problem..
I somehow missed the info about Ngene new version 1.1.2. will do.
Anat