Sampling and Data: Summary
Summary: This module provides an outline/review of key concepts related to statistical sampling and data. Note: This module is currently under revision, and its content is subject to change. This module is being prepared as part of a statistics textbook that will be available for the Fall 2008 semester.
Statistics
- Deals with the collection, analysis, interpretation, and presentation of data
Probability
- Mathematical tool used to study randomness
Key Terms
- Population
- Parameter
- Sample
- Statistic
- Variable
- Data
Types of Data
- Quantitative
- a number
- Discrete (You count it)
- Continuous (You measure it)
- Qualitative
- A category (words)
Sampling with Replacement
- A member of the population may be chosen more than once
Sampling without Replacement
- A member of the population may be chosen only once
Random Sampling
- Each member of the population has an equal chance of being selected
Sampling Methods
- Random
- Simple random sample
- Stratified sample
- Cluster sample
- Systematic sample
- Not Random
- Convenience Sample
Note:
Samples must be representative of the population from which they come. They must have the same characteristics. However, they may vary but still represent the same population
Frequency, Relative Frequency, and Cumulative Relative Frequency
- Frequency (freq. or F)
- The number of times an answer occurs
- Relative Frequency (rel. freq. or RF)
- The proportion of times an answer occurs
- Can be interpreted as a fraction, decimal, or percent
- Cumulative Relative Frequencies (cum. rel. freq. or cum RF)
- An accumulation of the previous relative frequencies
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Last edited by Jonathan Emmons on Apr 29, 2008 3:00 pm GMT-5.