<prompt> Translate the following text to EnglishKila kaya inadhaniwa kuwa na kazi ya mahitaji kwa kila bidhaa ambayo inategemea bei ya bidhaa zote, matumizi ya jumla ya bajeti ya kaya na sifa za kawaida na zisizoonekana za nyumba.  <response>: Each household is assumed to have a demand function for each good which depends on the prices of all goods, the households budgeted total expenditure and observable and unobservable characteristics of the household 