1) The fact that a person says that s/he would buy the product for the given price does not necessarily mean that s/he will actually do it. It might also not automatically mean that they can afford it, despite seeing the value (i.e. the different between ‘willing’ and ‘able’). To some extent, the other way round might also apply – a person who initially refuses to pay the price might decide to do so once s/he is more convinced of the product/ service's benefits. Despite these 'inaccuracies', the data provided by the indicator are essential for any marketing-related activities that introduce new or promote existing products.
2) To avoid any misunderstanding, if you ask about a product, show the respondent the product (or its photo).
3) In case you are interested in people's willingness to pay for a new or locally unfamiliar product/ service which might be difficult for the target population to imagine, introduce the product/ service first, describe its benefits and only then ask about the respondent's willingness to pay (it is a challenging task for the respondents to decide how much they would pay for a product/ service they are not familiar with).
4) Consider asking people why they would not pay a higher price than the one they stated (it can show you what they perceive as the product / service’s weakness).
5) The price you inquire about should be the real price of the given product.
6) The indicator assesses willingness to pay by using a simple customer survey method. There is a range of other methods you can use, such as experimental auctions. To learn more, read A Review of Methods for Measuring Willingness-to-Pay (see link below).