Frequently Asked Questions

Upon thoughtful consideration of the sample survey approach, several questions may come to mind. This section addresses several commonly asked questions in fairly general terms. As noted in the introduction, additional technical details are in a series of methods manuals.

Why implement probability survey designs? (PDF, 2pp, 58KB)

Which Design: Probability or Targeted State-wide or Regional? (PDF, 26pp, 68MB)

Questions concerning Survey Sampling

• Random sites selection
• Addressing Target population and sub-populations
• Surveys with Rotating basin design
• Sample surveys to identify waterbodies impaired, i.e. 303(d)

• Survey Approaches
• Target populations
• Importance of Subpopulations
• Stratification and Subpopulations
• Sample frame
• Sample surveys and census
• Probability Sampling
• Number of sample sites
• Sites selection
• Sample size of 50
• Response designs and plot level considerations
• General statistical books on survey designs

• Enhancing sampling intensity in special interest areas
• Estimating the resource extent with sample survey data
• Estimates of average condition and estimates of proportion
• Known confidence
• Size of the confidence interval
• Target population size and confidence intervals
• Integrating probability sample survey and targeted monitoring data