Data processing and information (AS Level) flashcards

Topic 1: Data processing and information

Data vs information

Data: raw facts and figures with no context, e.g. 37, Smith, 2410. Information: data given context and meaning, e.g. "Patient Smith's temperature is 37 °C".

Direct vs indirect data sources

Direct data is collected for the purpose at hand (questionnaires, interviews, data logging, observation). Indirect data was collected for another purpose and reused (census data, the electoral register, weather data).

Direct data: advantages and disadvantages

Relevant, current, of known accuracy and in the required format. But costly and slow to gather, and may need a large sample.

Name five factors that affect the quality of information

Accuracy, relevance, age, level of detail and completeness.

Symmetric vs asymmetric encryption

Symmetric: one secret key both encrypts and decrypts, so it must be shared securely; fast, but key sharing is the weak point. Asymmetric: a public key encrypts and only the matching private key decrypts; solves key sharing but is slower.

Validation vs verification

Validation: an automatic check that data is reasonable and of the correct type; it cannot show data is correct. Verification: a check that data has been accurately entered, transferred or copied.

Consistency check vs limit check

Consistency: one field is checked against another for a logical match, e.g. a start date before an end date. Limit: a value is checked against one boundary only, e.g. no more than 60 hours.

Hash total vs control total

Both are totals compared before and after data entry or transfer. A hash total has no meaning (e.g. a sum of employee numbers); a control total is meaningful (e.g. total hours worked in a batch).

Batch vs online vs real-time processing

Batch: data collected and processed later as a group (payroll, utility bills). Online: each transaction is processed as entered while the user waits (online shopping, EFT). Real-time: processed at once and the output affects the input (central heating, traffic lights).