experiment

(noun)

Something that is done that produces measurable results, called outcomes.

Related Terms

(noun)

A test under controlled conditions made to either demonstrate a known truth, examine the validity of a hypothesis, or determine the efficacy of something previously untried.

Related Terms

Examples of experiment in the following topics:

  • Introducing observational studies and experiments

    • There are two primary types of data collection: observational studies and experiments.
    • When researchers want to investigate the possibility of a causal connection, they conduct an experiment.
    • When individuals are randomly assigned to a group, the experiment is called a randomized experiment.
    • See the case study inSection 1.1 for another example of an experiment, though that study did not employ a placebo.
    • In general, association does not imply causation, and causation can only be inferred from a randomized experiment.

  • Selective Breeding

    • Selective breeding is a field concerned with testing hypotheses and theories of evolution by using controlled experiments.
    • One of the first to carry out a controlled evolution experiment was William Dallinger.
    • The experiment continues to this day, and is by now probably the largest controlled evolution experiment ever undertaken.
    • Since the inception of the experiment, the bacteria have grown for more than 50,000 generations.
    • Drawing of the incubator used by Dallinger in his evolution experiments.

  • Factorial Experiments: Two Factors

    • A full factorial experiment is an experiment whose design consists of two or more factors with discrete possible levels.
    • For the vast majority of factorial experiments, each factor has only two levels.
    • A factorial experiment can be analyzed using ANOVA or regression analysis.
    • The simplest factorial experiment contains two levels for each of two factors.
    • This table shows the notation used for a 2x2 factorial experiment.

  • Surveys or Experiments?

    • Uses of experiments vary considerably between the natural and social sciences.
    • In statistics, controlled experiments are often used.
    • Surveys and experiments are both techniques used in statistics.
    • When a businessman wants to market his products, it's a survey he will need and not an experiment.
    • Distinguish between when to use surveys and when to use experiments

  • Experimental Design

    • A methodology for designing experiments was proposed by Ronald A.
    • The random assignment of individuals to groups (or conditions within a group) distinguishes a rigorous, "true" experiment from an adequate, but less-than-rigorous, "quasi-experiment".
    • Factorial experiments: Use of factorial experiments instead of the one-factor-at-a-time method.
    • Analysis of experiment design is built on the foundation of the analysis of variance, a collection of models that partition the observed variance into components, according to what factors the experiment must estimate or test.
    • Outline the methodology for designing experiments in terms of comparison, randomization, replication, blocking, orthogonality, and factorial experiments

  • Exercises

    • Two experiments investigated the same variables but one of the experiment had subject who differed greatly from each other whereas the subjects in the other experiment were relatively homogeneous.
    • Which experiment would likely have the larger value of g?

  • Categorical Data and the Multinomial Experiment

    • The multinomial experiment is the test of the null hypothesis that the parameters of a multinomial distribution equal specified values.
    • In statistics, the multinomial experiment is the test of the null hypothesis that the parameters of a multinomial distribution equal specified values.
    • It is really an extension of the binomial experiment, where there were only two categories: success or failure.
    • One example of a multinomial experiment is asking which of six candidates a voter preferred in an election.

  • Introduction to testing for independence in two-way tables (special topic)

    • Google is constantly running experiments to test new search algorithms.
    • Google regularly runs experiments in this manner to help improve their search engine.
    • What is the ultimate goal of the Google experiment?
    • In this experiment, the explanatory variable is the search algorithm.
    • Table 6.16 provides the results from the experiment.

  • Analysis of Variance Designs

    • Be able to identify the factors and levels of each factor from a description of an experiment
    • In this experiment, "Type of Smile" is the independent variable.
    • Therefore, "Type of Smile" is the factor in this experiment.
    • If an experiment has two factors, then the ANOVA is called a two-way ANOVA.
    • For example, suppose an experiment on the effects of age and gender on reading speed were conducted using three age groups (8 years, 10 years, and 12 years) and the two genders (male and female).

  • Statistical Controls

    • Without a control group, the experiment cannot determine whether the fertilizer-treated plants grow more than they would have if untreated.
    • Ideally, all variables in an experiment will be controlled (accounted for by the control measurements) and none will be uncontrolled.
    • In such an experiment, if all the controls work as expected, it is possible to conclude that the experiment is working as intended and that the results of the experiment are due to the effect of the variable being tested.
    • Controlled experiments can be performed when it is difficult to exactly control all the conditions in an experiment.
    • Classify scientific controls and identify how they are used in experiments.