Data and information
- Data is raw facts and figures with no context, such as 12, 15 and 9. Information is data that has been processed so it has meaning, such as 'the average temperature this week was 12 °C'.
- Common data types: text, number (integer or real), currency, date/time and Boolean (yes/no).
Collecting data
- Primary data is collected first-hand for a purpose, using questionnaires, surveys, interviews, observations or sensors. It is relevant and up to date, but takes time and money to collect.
- Secondary data was collected by someone else, such as websites, books, published statistics or existing databases. It is quick and cheap to get, but may be out of date, biased or not exactly what you need.
Storing and checking data
- Data can be stored in spreadsheets, flat-file databases (one table), relational databases (linked tables) or files such as CSV files.
- Validation checks that data is sensible: range, type, length, presence and format checks, and lookup checks (against a list of allowed values). It can't check that the data is actually correct.
- Verification checks that data was entered or copied correctly: double entry (typing it twice) and visual checks (proofreading against the original).
Testing
- A test plan lists each test, the test data, the expected result and the actual result. Test data should be normal, extreme (at the edges of the valid range) and erroneous (should be rejected).
- Testing checks that a product works and meets the user requirements. In user acceptance testing, real users try the product to check it meets their needs.
Key terms
- Data
- Raw facts and figures with no context.
- Information
- Data that has been processed so that it has meaning.
- Primary data
- Data collected first-hand for a specific purpose.
- Secondary data
- Data that has already been collected by someone else.
- Validation
- Checking that data is sensible and allowed.
- Verification
- Checking that data has been entered or copied correctly.
- Test plan
- A list of tests with the test data, the expected results and the actual results.
- Extreme data
- Test data at the edges of the valid range.