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.


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.

  1. Sampling Distribution

    A probability distribution of a statistic obtained through a ...
  2. Sampling Error

    A statistical error to which an analyst exposes a model simply ...
  3. Normal Distribution

    A probability distribution that plots all of its values in a ...
  4. Look-Ahead Bias

    Bias created by the use of information or data in a study or ...
  5. Survivorship Bias

    The tendency for mutual funds with poor performance to be dropped ...
  6. Attribute Bias

    The tendency of stocks selected by a quantitative technique or ...
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  1. What is the criteria for a simple random sample?

    Simple random sampling is the most basic form of sampling and can be a component of more precise, more complex sampling methods. ... Read Full Answer >>
  2. What are the best selection methods for creating a simple random sample?

    The best selection methods for selecting a simple random sample are the lottery method, using a random number table or having ... Read Full Answer >>
  3. 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 >>
  4. Do plane tickets get cheaper closer to the date of departure?

    The price of flights usually increases one month prior to the date of departure. Flights are usually cheapest between three ... Read Full Answer >>
  5. Is Colombia an emerging market economy?

    Colombia meets the criteria of an emerging market economy. The South American country has a much lower gross domestic product, ... Read Full Answer >>
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    The common assumptions made when doing a t-test include those regarding the scale of measurement, random sampling, normality ... Read Full Answer >>

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