DEFINITION of 'Sample'
A subset containing the characteristics of a larger population. Samples are used in statistical testing when population sizes are too large for the test to include all possible members or observations. A sample should represent the whole population and not reflect bias toward a specific attribute.
INVESTOPEDIA EXPLAINS 'Sample'
A sample is a smaller, manageable version of a larger group. For example, if you wanted to test an investment strategy on past stock data, you would have an enormous number of stocks to test. Instead of testing the strategy on every stock, you would use a sample, which allows you to draw statistical insights from a smaller group of stocks. The sample should not contain any bias, such as the survivorship bias, where you might only use stocks that have survived the entire length of time you wish to test. Choosing a sample randomly should eliminate the possibilities of bias.

Sampling Distribution
A probability distribution of a statistic obtained through a ... 
Sampling Error
A statistical error to which an analyst exposes a model simply ... 
Normal Distribution
A probability distribution that plots all of its values in a ... 
LookAhead Bias
Bias created by the use of information or data in a study or ... 
Survivorship Bias
The tendency for mutual funds with poor performance to be dropped ... 
Attribute Bias
The tendency of stocks selected by a quantitative technique or ...

What are some examples of stratified random sampling?
Simple random sampling is a sample of individuals that exist in a population; the individuals are randomly selected from ... Read Full Answer >> 
What are the disadvantages of using a simple random sample to approximate a larger ...
Simple random sampling statistically measures a subset of individuals selected from a larger group or population to approximate ... Read Full Answer >> 
What is the difference between the expected return and the standard deviation of ...
Expected return and standard deviation are two statistical measures that can be used to analyze a portfolio. The expected ... Read Full Answer >> 
How do you calculate the geometric mean to assess portfolio performance?
The geometric mean is used to calculate the central tendency of a set of numbers. It is the average of the logarithmic values ... Read Full Answer >> 
What is the difference between a simple random sample and a stratified random sample?
Simple random samples and stratified random samples differ in how the sample is drawn from the overall population of data. ... Read Full Answer >> 
What are the advantages and disadvantages of using systematic sampling?
As a statistical sampling method, systematic sampling is simpler and more straightforward than random sampling. It can also ... Read Full Answer >>

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