Human beings can not be totally objective since we all have preconceptions about the world. You can only be really objective if you know nothing about a topic since knowledge on a topic creates opinions that influence preconceptions. This is also why every effort is made for juries to know little or nothing about the case in advance. You can only be totally objective if you are totally ignorant.
Dealing with data involves three steps collection, organizing and interpreting Collecting data includes measuring and recording and it is the most objective part of science. Since much of this is done by machines it is where true scientific objectivity is found. Even this process is not totally objective since the selection of data to be tested is not always objective and is often based on the theory being used says to look for. This part of the process is still the most objective. Organizing Data includes the categorizing of data sets. As soon as an organizing system exists it influences how the data is seen and this causes a loss of objectivity. The interpretation of data depends on the theoretical system being used to do the interpretation because different theoretical system produces different interpretations. Scientists using different theoretical systems on the same data can produce different and even contradicting interpretations and a flawed theoretical system causes flawed interpretation,