How to deal with multiple currencies in ACBC summarized price function

Question

We conducted a web survey with severel different currencies (n=7).

We built up an ACBC with 8 Attributes, 1 as summarized price. The component and base prices are moved in via unverified perl and several lists with the specific component price at the specific currency.

The study works great - each respondent gets the prices in his own currency without the need to conduct several studies.

The dataset writes the numerical price values in Design Variables (sys_ACBC_..._designX) as it´s pasted in the list:
[[37,5,2,3,1,2,1,1,200200] <- e.g. last number = summed price in SEK, not in EUR

My question is:
Am I forced to recode this currency-specific prices in the SQLITE Databes-File before i can estimate part-worths within the HB Tool?

Why do i get an error when i want to estimate my part worths? SSI says "an error occured, the price Values have not been set for summed pricing attribute."

In the dialog modelling the price function (HB Settings>Attribute Information>Coding & Level information)  i am not allowed to write price levels, with looping error message "please enter at least two price values." After that, i have to kill SSI via task manager...

Can i handle that mistake with the mentioned recoding of currency-specific prices within the SQLITE database @ Design-variables?

Answer 1

The looping error "Please enter at least two price values" was a user interface bug that was fixed in version 8.1.  Having only SSI Script in pricing fields would cause this error.  For some reason it did not make it into the release notes -- I will add it.  Please download the latest version and you should be able to add the price values.

Answer 2

Don't forget that there is more to this than just getting the prices to display properly within the software; there are analysis issues with the part-worth utilities.  With HB estimation, each respondent "borrows" some information from the other respondents to stabilize estimates.  If one person uses a currency 1/3 the magnitude of another respondent, then the price slope (the utility) will likely be about 3x the utility of the other respondent (assuming these respondents have fundamentally the same price sensitivity).  This can cause bias in the utility estimates, especially for respondents whose scaling of their currency is quite different from the mean scaling of currency.

With the market simulator, a product concept will need to be specified in price units.

So, the easiest way to avoid troubles if customizing the price as you are doing is to make sure you divide the respondents into different datasets at the back end and estimate the utilities (plus build the market simulators) unique to each currency group.

Comments

Dear Gary,
dear Bryan,

thank you for your helpful & fast answers. Due to small sample sizes (CAPI & B2B study) we want to have the flexibility to estimate utilities with full sample and make double checks with each country-specific HB run.

As i mentioned earlier, i´d try to recode the price values within the SQLITE Database set before I run HB to get standardized currency Values in one currency again. As far as I know, every Design-Information is stored in the Dataset in this "sys_ACBC_..._designX" Variable-Arrays? (as you mentioned - assuming the same price sensitivity)

Nevertheless - if this causes quite more issues in HB runs than expected by me - we´d be fine with country specific runs, we set up the study with enough tasks even for monotone regression so HB should handle n~20 per country...

Thanks in advance for your comments,

Sven

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Yes, design information is stored in sys_ACBC_..._designX.  Don't forget the BYO design, which is stored in <exercisename>_BYO_X where X is the attribute number.