Sample is a subset of observations/items that are drawn from a universal set (usually referred to as the 'population'). Use of samples is a common practice in data validation exercises, statistics and quantitative research. It is preferred to work with a sample rather than the population due to the ever existing constraints of time and money. Every validation test requires a certain number of minimum observations in the sample for the test to be effective.
Control Plan is a written document providing details of control methods for product and process characteristics. Its purpose is to minimize variation in both product and process characteristics. It is a key deliverable under PPAP requirements as well as in Control phase in DMAIC project. Control plan essentially covers the following elements
1. Characteristics and/or inputs (both product and process) to be controlled
2. Tolerances and trigger points for these inputs
3. Methods or actions required to keep the inputs within control
4. Escalation and response plan in case the inputs go out tolerance limits
A control plan is a live document i.e. it has to be revised following changes in either the product or process characteristics
Applause for all the respondents- Prashanth Datta.
Also review the answer provided by Mr Venugopal R, Benchmark Six Sigma's in-house expert.