guess·work 
/ˈgɛsˌwɚk/ noun
/ˈgɛsˌwɚk/ noun [noncount] : the act or process of finding an answer by guessing
▪ This book takes the guesswork out of buying a home. [=it gives you the information you need so that you can be sure about what to do] ▪ Calculating the drug's long-term effects is pure guesswork.
▪ This book takes the guesswork out of buying a home. [=it gives you the information you need so that you can be sure about what to do] ▪ Calculating the drug's long-term effects is pure guesswork.
