Any information found in a database has been memorized in some way starting from a source. Memorization and source are both subject to a series of factors that lead to errors, inaccuracies and omissions.
The extreme fragility of memorization processes
Both optical reading and manual input of information leave room for a multiplicity of errors.
All the automatic data acquisition tools are still extremely imprecise. If optical reading of printed characters involves a 25-30% average of errors, imagine what the percentage is for handwritten data. Manual data input process is usually carried out by an operator who reads the information written on a document or listens directly to a speaker; no matter how careful the operator is, this digital data transcription process leads to inaccuracies that affect the quality of the acquired data.
The subjective variable
Everybody is different, thank goodness! Because each of us has his/her own personality, we communicate the same information in a completely different manner. A person who writes down information regarding him/herself or others, always does this with a touch of creativity. Moreover, each person changes in the course of time, and this means that he/she will communicate the same information differently depending on the moment (hurry, attention level, emotional state, etc.).