Deterministic and Random Experiment

Classification of Experiments


An act of conducting a controlled test or investigation.

Classification of Experiments based on the number of results/outcomes

An experiment results in some outcome. The possible results/outcomes of an experiment may be one or more. Based on the number of possible results in an experiment, we classify the experiments into two as
  1. Deterministic and
  2. Probabilistic.

Deterministic/Predictable Experiment

Experiments which have only one possible result or outcome i.e. exepriment whose result is certain or unique are called deterministic or predictable experiments. The result of these experiments is predictable with certainty and is known prior to its conduct.

This approach stipulates that the conditions under which the experiment is conducted would determine its result.


The experiments that we conduct to verify the laws of science or established laws of other fields of study are the best examples for these.
  1. An experiment conducted to verify the Newton's Laws of Motion.
  2. An experiment conducted to verify the Economic Law of Demand.

Probabilistic/Indeterministic/Unpredictable Experiment

Experiments which have more than one possible results or outcomes i.e. whose result is uncertain are called indeterministic or unpredictable or Probabilistic experiments.

The actual result in a particular conduction of the experiment would be one of those possible results. Whatever may be the conditions under which we conduct the experiment, we can only say that the result would be one of the possible results. We cannot ensure a certain result by performing the experiment under certain conditions or in a certain method.

The quantitative measure of certainty regarding one or more outcomes of these experiments is what we call "Probability".

Random Experiment, At Random

At Random


  1. Without giving preference or priority to any case i.e. without any bias for any case.
  2. Lacking any definite plan or order or purpose;
  3. Governed by or depending on chance.

A Random experiment is is a probabilistic experiment i.e. an experiment whose result/outcome is uncertain. The experiment results in two or more outcomes. The result/outcome of the experiment would be one of the possible outcomes. It cannot be predicted prior to its conduct.

The different possible outcomes of the experiment can be known or assessed. But it would not be possible to predict the occurrence of a particular outcome at any particular execution of the experiment.


  1. Tossing a coin

    obverse sidereverse side
    Coin Obverse [HEAD] Coin Reverse [TAIL]

    In the experiment of tossing a coin, there are two possible outcomes i.e. getting a Head or getting a Tail. Though we know the two possible outcomes, we cannot predict the occurrence of a head or a tail. We cannot say that a tail would appear if we throw the coin in a particular manner and so on.

  2. Rolling a die/dice

    Die/Dice Six Faces
    Six Faces of the Dice

    In the experiment of rolling a die/dice, there are six possible outcomes i.e. the die showing up 1, the die showing up 2, ... , the die showing up 6. Though we know the six possible outcomes, we cannot predict that a particular number will appear on the face of the dice. We cannot make a particular number appear on the face of the dice by throwing/rolling it in a particular manner.

... 123 ...