I have the following Bibtex source:
@Book{sarndal_estimation_2005,
Title = {Estimation in {Surveys} with {Nonresponse}},
Author = {S{\"a}rndal, Carl-Erik and Lundstr{\"o}m, Sixten},
Publisher = {Wiley},
Year = {2005},
Address = {Chichester}
I use the following Latex preamble
\usepackage[backend=biber, style=apa, sorting=nyt, sortcites=true]{biblatex}
However the umlaute in the author names are simply omitted despite the correct representation in bibtex code. Do I need to enter them differently for biblatex?

\usepackage[utf8]{inputenc}and\usepackage[T1]{fontenc}? Or neither. – egreg Jun 14 '16 at 12:08