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linking levels in Discrete Choice experiment

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Occasional Contributor
Posts: 6

linking levels in Discrete Choice experiment

Dear all,

I am going to conduct a discrete choice experiment about tariff choice.
In the experiment, i want to include a discount for contract duration, that is, the longer the contract the higher the discount on final price.

Thus, i have the attribute CONTRACT with levels 0, 12 and 24, and i have the attribute PRICE I with levels of +5, 0 and -5.

I now want to link the levels of the first attribute to the ones of the second, so that every time an alternative possesses the CONTRACT level 24, the PRICE I level is -5, for instance.

I hope someone can tell me how i can program this, and if it is doable at all.

Thanks a lot!
Grand Advisor
Posts: 9,446

Re: linking levels in Discrete Choice experiment

Hi. I do not understand your purpose total.
Plz, give an example and what target do you need to achieve.
Occasional Contributor
Posts: 6

Re: linking levels in Discrete Choice experiment

Okay, let me explain it to you in more detail.

I have a discrete choice / choice-based conjoint experiment with the 4 attributes:
- QoS
- speed
- contract duration (0 / 12 / 24)
- max. usage in giga byte (7.5 / 10 / 12.5)

Another attribute is supposed to be
- price

However, using this setting, awkward combinations would come up. Thus, I was planning to delete the initial price attribute and replace it by two other price attributes:
- price I (price per giga byte)
- price II (discount for longer contract duration)

Price I:
- 1 level: $3.99
- is to be multiplied with a corresponding "max usage in gb" level (e.g. "10")

Price II:
- 2 levels: "$5" and "$0"
- "$5" is only allowed to show up in combination with the level "0" of the "contract duration" attribute
- "$0" is only allowed to show up in combination with the levels "12" and "24" of the "contract duration" attribute
- is to be added to the result of the Price I multiplikation above.

Here is one example:

Alternative 1
QoS "good"
Speed "very fast"
Contract "0 months"
max. usage "10 gb"
price I "$39.90" (as 10x$3.99)
price II "5$"


Alternative 2
QoS "excellent"
Speed "normal"
contract "12 months"
max. usage "12.5 gb"
price I "$49.90" (as 12.5x$3.99)
price II "$0"

Attributes price I & II are for the design only. In the questionnaire, the respondent will see one uniform price attribute only.

What I need to know is, how do I assign the levels of "price II" to the corresponding levels of "contract duration", as "$5" is not supposed to be combined with "12" and "24", but only with "0".

I hope this made my problem more clear. Many thanks in advance!
Grand Advisor
Posts: 9,446

Re: linking levels in Discrete Choice experiment

Sorry. Respond it so late.
But not see what your data look like and what your output look like.
Is your contract duration numeric variable?
It seems to be a format problem.
But I am not sure whether the following is what you need.

[pre]
proc format;
invalue pricefmt
0 = 5
12,24= 0;
run;

..................
price_two = input(contract_duration_value,pricfmt.);
format price_two dollar4.;

[/pre]



Ksharp
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