How is premium data different from free data?

A premium data feed is usually "better" than its free data feed equivalents because:

  • It is carefully quality-controlled by a person or company to ensure accuracy and consistency and to eliminate gaps and errors. (Correctness)
  • It is manually or semi-manually curated and organized by a person or company; this means better documentation, structure, nomenclature and general ease of use. (Organization)
  • It is updated immediately when new information becomes available. (Timeliness)
  • It offers unique or proprietary data that simply cannot be obtained for free because it is manufactured by a private company and thus not in the public domain. (Uniqueness)

In summary, premium data feeds on Quandl are of a higher quality than their free equivalents because they are built and continually maintained by domain experts.