Men det gælder for dem alle, at de er begrænset enten til en enkelt sektor eller et enkelt land, eller at de bygger på et empirisk grundlag, der faktisk er så gammelt, at det er svært at anvende det til en generalisering.
What unites all of the investigations, however, is the fact that they are either limited to specific sectors or nationally or that they are founded precisely on an empirical basis which basically goes so far back that it is barely suitable for generalisation purposes.