Podcast
Questions and Answers
What is the primary characteristic of systematic sampling?
What is the primary characteristic of systematic sampling?
- Samples are taken from homogenous populations only.
- Samples are selected based on the researcher's judgment.
- Samples must be collected continuously without gaps.
- Samples are taken at random intervals. (correct)
What does stratified sampling involve?
What does stratified sampling involve?
- Selecting entire subgroups randomly.
- Collecting samples from heterogeneous populations only.
- Randomly choosing individuals without any subgroup consideration.
- Dividing the population into subgroups and selecting from each. (correct)
Which sampling method combines multiple grab samples into one before analysis?
Which sampling method combines multiple grab samples into one before analysis?
- Grab sampling
- In situ sampling
- Judgmental sampling
- Composite sampling (correct)
What is one disadvantage of composite sampling?
What is one disadvantage of composite sampling?
In what situation is grab sampling most appropriate?
In what situation is grab sampling most appropriate?
How does in situ sampling differ from other sampling methods?
How does in situ sampling differ from other sampling methods?
What is the advantage of using systematic grab sampling over simple grab sampling in a heterogeneous population?
What is the advantage of using systematic grab sampling over simple grab sampling in a heterogeneous population?
Which of the following is NOT a common method for obtaining samples?
Which of the following is NOT a common method for obtaining samples?
What is a major disadvantage of grab samples and composite samples?
What is a major disadvantage of grab samples and composite samples?
What is the main purpose of in situ sampling?
What is the main purpose of in situ sampling?
Which step is NOT involved in sampling bulk material?
Which step is NOT involved in sampling bulk material?
What is the key characteristic of a homogeneous target population during sampling?
What is the key characteristic of a homogeneous target population during sampling?
What is a significant error source in sample collection prior to trace analysis?
What is a significant error source in sample collection prior to trace analysis?
Why is it important to select multiple individual samples from different locations in a heterogeneous population?
Why is it important to select multiple individual samples from different locations in a heterogeneous population?
Why is it important to minimize adsorption of analytes during sample collection?
Why is it important to minimize adsorption of analytes during sample collection?
Which of the following methods ensures that every member of the population has an equal chance of selection?
Which of the following methods ensures that every member of the population has an equal chance of selection?
Which material is recommended for dissecting human and animal tissues during sample collection?
Which material is recommended for dissecting human and animal tissues during sample collection?
What is a common issue that arises when sampling is done in a haphazard manner?
What is a common issue that arises when sampling is done in a haphazard manner?
What factor must be considered regarding the time of sampling?
What factor must be considered regarding the time of sampling?
What is described by the term 'sampling error'?
What is described by the term 'sampling error'?
What is the correct procedure for reducing a gross sample in laboratory sampling?
What is the correct procedure for reducing a gross sample in laboratory sampling?
During which type of sampling do researchers rely on their personal judgment to select units?
During which type of sampling do researchers rely on their personal judgment to select units?
Which sampling method typically gives a more accurate representation of a complex system such as a lake affected by pollution?
Which sampling method typically gives a more accurate representation of a complex system such as a lake affected by pollution?
In sampling techniques, what does in situ sampling typically refer to?
In sampling techniques, what does in situ sampling typically refer to?
Study Notes
Sampling Methods
- Systematic Sampling - select first sample randomly and then take samples at intervals, this could be every 5th, 10th, or even every 5 minutes, 10 minutes
- Stratified Sampling - divide the population into subgroups and then select samples from each subgroup
- Cluster Sampling - divide the population into clusters (each cluster should have similar characteristics to the whole populations) and then randomly select entire clusters
Types of Samples
- Grab Sample - take a portion of the population at a specific time and location, this provides a snapshot of the population
- Composite Sample - combine several grab samples, used to determine the population's average composition over time or space
- In Situ Sample - uses an analytical sensor to continuously monitor a target population without needing to remove samples
Error Sources Prior to Total Element Determination
- Contamination - take care to avoid contamination of all tools and vessels, especially with samples that have very low trace element levels (like blood, urine, or seawater) . The time of sampling can be very important especially for body fluids or fresh waters (rivers or lakes)
- Time of sampling - consider the time of day.
Sampling Methods (Techniques)
- Probability (Random) Sampling - every member of the population has the same chance of being selected, this method minimizes bias
- Non-Probability Sampling - use personal judgment to select samples,
- Simple Random Sampling - every sample has an equal chance of being selected
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Description
Test your understanding of various sampling methods with this quiz. It covers systematic, stratified, and cluster sampling techniques, along with types of samples such as grab, composite, and in situ samples. Additionally, it addresses potential errors from contamination in sampling processes.
