The main difficulty with financial accounts lies in the fact that they are usually prepared for a past period, where accounting data problems can, according to Dyson (2004), be grouped around three major groups of samples:
1. Absolute. Data in the financial accounts have been presented as absolute amounts and limited to quantitative matters.
2. Contextual. Data cannot be analyzed in isolation, but only in a comparative perspective, which opens up the issue of the criteria for collecting the historical data. It is difficult to show a trend without considering a three-year period, but on the other hand, if the analyzed period exceeds five years, there is a risk that the data will be old and thus less reliable.
3. Structural. Since the financial accounts, even when very detailed, contain a limited quantity of information, they frequently require arbitrary assessments on relevant issues, such as bad debts, depreciation and stock valuation.