Statistics Chapter 1.3 Random Sampling

Questions and Answers

Define random sampling.

The process of using chance to select individuals from a population to be included in the sample.

For the results of a survey to be reliable, what must the characteristics of the individuals in the sample consist of?

Must be representative of the characteristics of the individuals in the population.

What is the key to obtaining a sample representative of a population?

Let chance or randomness play a role in dictating which individuals are in the sample.

What happens if convenience is used to obtain a sample?

The results in the survey become meaningless. Signup and view all the answers

What are the four basic sampling techniques?

<ol> <li>Simple random sampling 2. Stratified sampling 3. Systematic sampling 4. Cluster sampling.</li> </ol> Signup and view all the answers

What is the most basic sample survey design?

Simple random sampling. Signup and view all the answers

What is simple random sampling like?

Selecting names from a hat. Signup and view all the answers

What is the definition of a simple random sample?

A sample of size n from a population of size N is obtained through simple random sampling if every possible sample of size n has an equally likely chance of occurring. Signup and view all the answers

Is the number of individuals in the sample always less than the number of individuals in the population?

True Signup and view all the answers

What does the word sample refer to?

Refers to the individuals in the sample. Signup and view all the answers

What is a frame?

A list of all the individuals within the population. Signup and view all the answers

How do you select the individuals in a simple random sample?

Assign each individual in the population a unique number between 1 and N. Signup and view all the answers

What does N represent when selecting the individuals in a simple random sample?

N represents the size of the population. Signup and view all the answers

What does n represent?

The size of the sample. Signup and view all the answers

What do you need in order to number the individuals in the population?

A frame. Signup and view all the answers

What happens to an individual in a sample without replacement?

The individual who is selected is removed from the population and cannot be chosen again. Signup and view all the answers

What happens to an individual in a sample with replacement?

A selected individual is placed back into the population and could be chosen a second time. Signup and view all the answers

What is a seed?

It's an initial point for the generator to creating random numbers. Signup and view all the answers

Study Notes

Random Sampling Basics

Random sampling is a method used to select individuals from a population using chance, ensuring all members have an equal opportunity to be chosen.
For survey results to be trustworthy, the sample characteristics must reflect those of the broader population.

Importance of Chance in Sampling

A sample needs randomness to be representative; using convenience leads to biased results and meaningless data.
Simple random sampling is the foundational technique for gathering unbiased samples.

Sampling Techniques

Four primary sampling techniques:
- Simple random sampling
- Stratified sampling
- Systematic sampling
- Cluster sampling

Characteristics of Simple Random Sampling

Simple random sampling can be likened to drawing names from a hat.
In this method, each potential sample size has an equal probability of selection.
Sample size (n) is always less than the population size (N).

Sample and Frame Definitions

A sample consists of individuals selected to represent the larger population.
A frame is a comprehensive list of all individuals in the population, essential for creating a sample.

Selection Process

Individuals in a simple random sample are assigned unique numbers, enabling random selection.
N denotes the population size, while n indicates the sample size needed for study.

Replacement in Sampling

In sampling without replacement, selected individuals are removed from the population and cannot be chosen again.
In sampling with replacement, selected individuals remain in the population, allowing for potential re-selection.

Additional Concepts

A seed is the initial point used by random number generators to ensure variability in selection.

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Test your knowledge on simple random sampling with these flashcards. Understand the concept, characteristics, and importance of representative samples in survey reliability. Perfect for students studying basic statistics!