1. Sampling Plan Model - Introduction For describing sampling plans for surveys and other statistical activities Handles all kinds of samples: Non-probability samples Probability samples Traditional – e.g., SRS, SSRS Model based Multi-stage Including stages with more than one frame Simple and direct 3 classes 3 relationships Few attributes

2. Sampling Plan Model - Introduction Frames are not described in this model. Model-based probability sampling is describable. Non-probability based sampling is describable. In a PPS sample, for instance, the inclusion probabilities are (possibly) different for each sample unit, and, so, these may be confidential. In this case, a pointer or reference to them is all that should be supplied.

3. Model - Class Diagram Sample Overview Stage Stage Sample [0..1] [0..N] follows [1..N] [1..1] [0..1]

4. Sampling Plan – Model Description Sample Overview is a composition of Stages. Stages are not reusable. Stage is an aggregation of one or more Stage Samples. Stage Samples may be created and reused. Note – multiple Stage Samples are allowed at each Stage. Therefore, it is possible to develop the sample plan in parts, using multiple frames. In a multi-stage design, each Stage Sample follows a Stage Sample in sequence from the next earlier Stage. So, as a constraint, the follows relation is required in multi-stage Sampling Plans. Stage Samples describe the sampling at each stage: number of units; sampling type; probabilities of inclusion (if necessary); etc. The type attribute indicates whether the sample is drawn under SRS, SSRS, PPS, SRSWR, etc.

5. Sampling Plan – Classes and Relations Classes – Stage Sample – plan for drawing a sample directly (in one step) from a single frame Stage – set of Stage Samples, each linked to a Stage Sample from the same prior stage Sample Overview – summary, including a set of stages, to draw a sample Relations – Composition (Sampling Overview is composed of Stages) A Stage Plan is contained in one and only one Sampling Overview A Sampling Overview contains one or more Stages Note – A Stage is not a reusable object. It exists only for a Sampling Overview.

6. Sampling Plan – Classes and Relations Relations – Aggregation (Stage Samples aggregate into a Stage) A Stage Sample may be contained in one and only one Stage A Stage may contain one or more Stage Samples Note – A Stage Sample may be reused. It can appear in a Stage in any Sampling Overview. Follows (Stage Samples follow another Stage Sample) A Stage Sample may succeed one and only one Stage Sample A Stage Sample may precede one or more Stage Samples Note – This relation ties a Stage Sample to the Stage and Stage Sample that precedes it. This way, a sequence of samples is conducted in stages.

7. Sample Overview– Attributes Name[1..1] text Target population[1..1] text Survey population[1..1] text Frame[1..1] text or pointer Type[1..1] {probability, non-probability} Size[1..1] positive integer Number of stages[1..1] positive integer Inclusion probabilities[0..N] real, fraction, pointer, or reference

8. Stage – Attributes Stage number[1..1] positive integer Number of samples / this stage[1..1] positive integer

9. Stage Sample – Attributes Survey population[1..1] text Frame[1..1] text or pointer Frame Population[1..1] text Size[1..1] positive integer Type[1..1] {SRS, SRSWR, SSRS, PPS, Sys, etc} Inclusion probabilities[0..N] real, fraction, pointer, or reference Strata[0..N] list (text) or pointer

10. Populations – Definitions and Examples Target, Survey, and Frame Populations Frame Population – the population covered by the frame Survey Population – the population the survey does measure Target Population – the population the survey is intended to measure Example – Labor force survey Frame population – occupied housing units Survey population – working age adults Target population – working age adults Example – Telephone survey of voters for an election Frame population – active residential and cell phone numbers Survey population – people eligible and likely to vote Target population – people that will vote (in some election)