I’m trying to investigate people’s health promotion behavior, but there is no well-developped survey quesionnaire in my language available. What should I do if I wanna use an english scale? So far as I know, I should get the permission to use the scale from the author, then do forward and backward translation. What else? Is there any book or literature which can provide some guide?
Permission is a necessary step, but the most important thing is that you can translate the scale correctly. There are many forms to do this, the most typical way is take the original scale (in the original language), and ask some expert, with a very strong knowledge over original language, translate the scale into your language. After that you can translate the translated scale into the original language again, comparing the two final versions. This procedure is called “inverse translation”, however, this is not the preferred system for some psychometricians. For instance, the authors of PISA test, didn’t use this procedure to translate it, they organised some teams of expert/translators who worked over the test in a separate way, then they compared the final versions, trying to solve conjointly the differences that appeared.
I recommend you download the free technical reports of PISA from its website, you will find really good advices.