SANA SHAIKH
By Sana Shaikh

BHMS and Yoga Trainer

07 May 2022
Medically reviewed by
Dhanashree Padhye
MA (Psychology)
Your Guide To Random Assignment In Psychology
Table of Contents

Have you been in a situation where massive chaos broke for some project of yours about who would work with who; then, to quiet the crowd down, your teacher decided to play a fair draw in which she would write the names of all the students on chits and mix the chits in a bowl, later picking a random chit out to decide who pairs with who?

This is a very relatable example of what Random Assignment is in Psychology.

How Do We Define Random Assignment?

Random Assignment is like a fair draw or lottery system used to randomly assign participants to an experimental group or control group of the experiment. This provides an unbiased, undisturbed, and fresh result at the end of the experiment. The key feature here is that through the Random Assignment provides an equal chance for the participants unless they have had personal fallbacks. (Krause, M.S. and Howard, K.I., 2003)

The dependent and independent variable

This assignment aims to investigate how manipulation of one factor causes a change in another factor. These factors are named as independent and dependent variables. An independent variable is one that doesn't change. Experiments are conducted to determine the effect of this variable. In contrast, a dependent variable is one that can be altered and modified on the basis of the independent variable. The effect of an independent variable upon the dependent variable is observed. This helps determine the relation between the two variables.

For example, an experiment is conducted to determine the effect of coffee on sleep. Here, the independent variable is coffee, while the dependent variable is sleep, as the alteration of coffee impacts sleep.

Psychologists prefer Random Assignment because it reduces any pre-judgmental and coordinative obstructions. The participants, in most cases, are strangers to each other, and this results in unbiased and critical data that implies the actual dependency of the dependent variable on the independent variable.

Why Is Random Assignment Of Importance?

These dependent and independent variables are studied and observed actively and passively by experimental and control groups to which the participants are randomly assigned. The participants in the experimental group are open to evaluation actively, while those in the control group cannot access it actively. (Krause, M.S. and Howard, K.I., 2003)

This is needed for two primary reasons:

  1. Creation of unbiased equivalent groups- When Random Assignment of participants is done, it eliminates the chances of discrimination and inequality amongst and with the participants. Participants from varied backgrounds (sex, race, age, status, occupation, and motivation) are randomly picked to perform a particular experiment.

Also, any judgment based on power and superiority is erased as well.

  1. Reliability of result- Due to the equivalency of participation, the chances of getting a reliable result increase.

E.g., if an experiment were to be conducted on the effect of coffee on sleep, participants would be placed randomly into two groups, one that would be asked to consume coffee and one that would not be, based on the record that both the groups match on all characteristic grounds except that one is provided with coffee and the other group isn't.

If the Random Assignment method is not used, there is a positive possibility to encounter errors in the end data.

Example Of Random Assignment

In an experiment on the effect of violent gaming (independent variable) on the behavior of children (dependent variable) conducted; you choose to use three groups:

  • A control group that is not exposed to violent games
  • One experimental group that is exposed to violent gaming for a short period of time
  • Second experimental group that is exposed to violent gaming for a reasonable amount of time

Random Assignment helps confirm that the groups don't differ in any systematic or biased manner. It ensures the experiment to be conducted reliably.

Example Of Non-Random Assignment

Suppose for an experiment; people were grouped based on their food preferences.

Here, those with a taste of spicy food would label Japanese cuisine as tasteless, while those with a preference for cakes over chocolates would label milk chocolates as overrated.

This would create a sense of biasness and would NOT lead to reliable results. If the results are in favor of a specific preference, it will create a sense of discrimination.

How is Random Assignment Applied?

The application is simple. The selection is made based on:

  • Chit shuffle- In this, chits with participant names are put inside a bowl and shuffled with hand. Then, one by one, chits are drawn out, and the participants are placed into groups accordingly.
  • Coin toss- With head assigned to control and tails assigned to experimental, a coin is tossed in front of each participant to decide who belongs to which group.
  • Random numbering- Similar to chit shuffle, each participant is given a number at random. Then, balls with numbers on them are placed in a tub. For the experimental group, balls are drawn at random till a specific amount is reached. The remaining participants are allotted to the control group.

The goal of Random Assignment is to observe the changes in one variable due to the variation in others, just like the intensity of exposure to violent gaming affecting the behavior of the children.

Once the researcher is set with the objectives of the assignment, the participants are divided and selected randomly by either of the lottery methods. Based on this, some participants will end up in the control group that does not consume the independent variable, while others are placed in the experimental groups, varying the intensity and occurrence of the independent variable.

By the end of the experiment, the researchers collect the data from the participants to determine the impact of the independent variable upon the dependent variable.

When NOT To Apply Random Assignment?

There are times when Random Assignment is considered unethical or irrelevant.

  • While comparing specific conditions- Suppose an experiment is to be held to determine the effect of antidepressants on men and women. Here, participants cannot be chosen at random. The only way to get the experiment done could be to analyze the participant's history in terms of medical records, mental condition, etc. Random Assignment here could create a chaotic result.
  • When it involves a "risk factor"- If an experiment is conducted on the effect of heavy drinking on mental health, it is highly unethical to choose, at random, some participants and ask them to fill up on alcohol for the sake of an experiment. This could lead to severe consequences.

What Could Be Done In Such Situations?

In situations where the application of Random Assignment is not possible, methods like "Quasi-experimental studies" could be used.

According to this method of study, you do NOT go ahead performing a risky experiment. Instead, you study and research upon the pre-existing conditions and results of the participants and derive a conclusion.

For the experiment of "effect of heavy drinking on mental health," you could refer to the studies of heavy drinkers being interrogated for surveys, experiments, studies, and so on. However, for the mild drinking and non-drinking part, you could use the Random Assignment method to derive a conclusion.

Bringing Up The Rear

Random Assignment plays a crucial role in psychology. It terminates any form of biased circumstance and behavior and also reduces systematic glitches.

Random Assignment method ensures unique, reliable, and unbiased data as a result and helps deformalize the effect of any internal dispute upon the experiment by selecting participates at random. Through the use of Random Assignment, the study of the human mind and behavior has become easier.

However, this method can NOT be applied everywhere. In places that include a specific demand or a risk factor, implementation of this method solely could generate a chaotic output. Nevertheless, using altering the application of Random Assignment could help get similar unbiased and reliable outputs.

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