<prompt> Translate the following text to EnglishKwa kila aina ya URS, thamani ya dola ilitokana na kutumia makadirio ya kati ya WTP IEc, 1994 ili kuepuka kila dalili katika kundi na kudhani WTP ni nyongeza.  <response>: A dollar value was derived for each type of URS, using mid-range estimates of WTP IEc, 1994 to avoid each symptom in the cluster and assuming WTPs are additive. 