Module 3

Question 1

2 question you need to ask when composing a sampling approach

Answer 1

1. What kinds of samples are needed

2. How many of them are needed

Question 2

Additional questions for sampling approach

Answer 2

• how will will the results be used?
• where to collect
• what containers
• how to preserve
• what preparations are necessary
• how to analyze(instruments,detectors, analytical methods)
• to to evaluate data

Question 3

What are the four principles for sampling plan

Answer 3

1. environmental samples must be representative of the portion of the environment being investigated
2. procedures for sampling and analysis influence each other, plans for sampling and analysis are codependent
3. Quality control samples must be representative of the environmental samples being analyzed
4. QCs used to assess amount of bias and imprecision in data from analysis of samples

Question 4

What is the order or error pyramid

Answer 4

1. data handing (top of pyramid)
2. Analysis
3. sample prep
4. sample handling
5. field sampling
6. pollutant distribution (bottom of pyramid)

Question 5

What is a DQOs

Answer 5

Data quality objectives are a process (or set of terms) that outline the overall uncertainty that can be tolerated in the project. Qualitative or quantitative.

The point is to make a corrective action if DQOs aren’t met
Work on principle 2

Question 6

What are the 2 major components of DQO process

Answer 6

1. very specifically state your question(a)

2. very specifically state amount of uncertainty your willing to tolerate

Question 7

7 steps of DQOs utilization

Answer 7

1. Problem
2. Identity decision required
3. identify inputs to decision
4. determine the boundaries of study
5. Develop a decision rule
6. develop uncertainty constraints
7. optimize the design for obtaining data

Question 8

Types of sampling techniques

Answer 8

1. random sampling
   
   • no bias
2. systematic random sampling

3.judgmental sampling

Question 9

Explain random sampling

Answer 9

Every sample of the population has an equal chance of being selected

-very expensive, unbiased, assumes samples are independent but spacially correlated, samples are farther apart then the range of correlation

Question 10

Explain what semi variogram is

Answer 10

A tool used to determine the number of samples required for a program to be considered statistically random.
-shows how distance between samples increases randomness
(Dist can be spatial or temporal)

Question 11

Explain systematic random sampling

Answer 11

Divides population it to homogeneous groups to reduce variance.
-groups divided into cells by Cartesian grid

-slightly more bias, used for contaminated land sites, drill wells, biological sampling

Question 12

Explain judgemental sampling

Answer 12

Most cost effective, most bias, based on prior history and visual site assessment,doesn’t factor in pollutant behaviour or migration

Question 13

Factors for choosing a sampling plan

Answer 13

1type of pollutant
2type of sampling device
3end use of data