Complex sentence: Sales of privately held companies are voluntarily reported by business brokers or unscientifically accumulated by private companies with the intent of re-selling the data, consequently the data is considered by many to be corrupted by sampling bias and of questionable reliability.
Split into simpler sentences: Sales of privately held companies are voluntarily reported by business brokers or unscientifically accumulated by private companies with the intent of re-selling the data. Consequently the data is considered by many to be corrupted by sampling bias and of questionable reliability.