The first thing you should learn is to understand traditional Norwegian naming patterns and practices.
Online study material to learn about Norwegian naming practices and patterns. http://homepages.rootsweb.ancestry.com/~norway/na12.htmlhttp://www.nndata.no/home/jborgos/names.htmhttp://www.norwayheritage.com/norwegian-names.htmhttp://www.nndata.no/home/jborgos/farms.htm
Then -- when people emigrated they could identify themselves as anything they liked. Some stuck with their traditional Norwegian names, some chose to adapt the spelling to a style better suited to their new home, and others chose names which take some research to understand why they chose those. Add on the strange family stories that have developed over time and you can have to do some work to understand where to start.