170135_inorganicventures_flipping

3:7 Sampling and sub-sampling

Different Approaches to Sampling

The following approaches may be specified in the sampling plan:

Ø Random - Random sampling means that any portion of the sample population has the same probability of being taken. Random sampling is often used for production operations that are continuous. It is also used with constraints, such as a the collection of a random sample during the first, middle, and last third of a production lot that must be analyzed separately to determine if the lot is homogeneous Ø Systematic - Systematic samples are collected at predetermined intervals that are defined in the sampling plan.

3:8 Sampling and sub-sampling

Different Approaches to Sampling (cont)

The following approaches may be specified in the sampling plan:

Ø Stra%fied - Stra?fied sampling involves specifica?on of depth, size, color, or some characteris?c that must be considered in mee?ng the objec?ve of the analysis. Ø Sequen%al - Sequen?al sampling is oGen used to determine if a product meets specifica?on. Ini?ally, samples are pulled in a ‘systema?c' fashion and the data is evaluated. If the product is well within specifica?on, no more sampling occurs. If the product is near the specifica?on limit (i.e. - the mean is in specifica?on, but the uncertainty of the measurement goes beyond the specifica?on range), then more samples are pulled to lower the uncertainty and to determine if specifica?on is realized..