Constant

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A constant, as its name suggests, is something that does not vary or change (or that may not be susceptible to variation or change).

Properties

• A constant has only one attribute or value.
• The search for constants is the ultimate goal in science. A scientific law (eg light in a vacuum travels at 300,000 km/seg) is a constant. As such, it allows us to predict properties based on such law, to use it as a premise in deductive sciences, and to use it as an assumption in inductive sciences.
• A main task in experimental research, however, is to control the variability of all but the research variables. This control is done by way of keeping all other variables as constants. Once this is achieved, it is possible to ascertain the relationship between the research variables, as these would be the only variables actually varying.
• Any variable can be made into a constant by reducing its expression to only one of its values.

For example, we could keep the temperature of a room constant at 35^o C during an experiment. In this case, temperature stops being a variable.

• A constant has no use in statistics. That is, anything that is or remains constant cannot be subjected to statistical analysis. Many researches, however, may take this property as meaning that a given constant is not relevant for predicting something, which is not always the case.

For example, if social research finds that children who don't go to school end up as criminals in adult life, while children who go to school do not, then this variable (child scholarization) can "predict" future criminality. If so, there will also be good reasons to make all children attend school, as this should reduce criminality in the future. Yet, once all children go to school, the original variable does not vary anymore, thus becoming a constant. A constant cannot be used for statistical analysis, thus it cannot be used for predicting future criminality, and, thus, it is removed from statistical models. This may be fine so far as scholarization continues. However, the lack of statistical significance may be interpreted as lack of relevance, which may lead to stopping the intervention, and this to an increase in criminality in the future. In this example, child scholarization, although a constant, predicts future criminality, even when it doesn't seem statistically significant.

How to make a constant

• A variable can be made into a constant by reducing its expression to only one of its values. Eg, gender can be made a constant by only choosing women for a particular research project; or temperature can be made a constant by keeping it at 35^o C throughout an experiment.

Did you understand?

+ Test yourself

• 1- You are doing research on how gender contributes to learning. You send out invitations for people to respond to your questionnaire, which you have put online for one month. At the end of that time, you download all responses and find that only men have answered your questionnaire. Therefore, what happens to "gender"?
  • a- Gender is still the most important variable in your research.¹
  • b- Gender has become a constant. Anything you conclude can be considered a scientific law.²
  • c- Gender has become a constant. Thus, it has lost any predictive power in your research.³
  • d- Gender appears to be a constant but it is still a variable. This is so because you did not restrict the questionnaire to men only; it was just a coincidence.⁴

• 2- Regarding constants, science and statistics, which of the following statements is correct?
  • a- Constants have no place in statistics. Therefore, statistic-based disciplines are not scientific.⁵
  • b- You need variables to make good science.⁶
  • c- Statistics rely on variables to progress science.⁷

Test answers

1. Incorrect. Gender has, indeed, become a "de facto" constant.

2. Incorrect. Indeed, gender has become a constant, but this doesn't make your results scientific laws.

3. Correct. Because you have no women in your sample, you cannot assess any learning differences related to gender.

4. Incorrect. It doesn't matter that you didn't want a constant. The variable became a constant simply because only men, by chance or otherwise, replied to the questionnaire.

5. Incorrect. It is true that constants cannot be used in statistics. Yet, these disciplines still search for constants (or laws). For example, a "constant" or "law" may be that women perform certain tasks better than men. Yet, to establish and replicate such findings you still need gender as a variable.

6. Incorrect. Once a scientific law has been established as a constant, such law can be used to predict things (eg how long would it take for the light of the Sun to reach the outer limits of the Solar System), include it into new formulas or hypotheses (eg to calculate the distance between stars in the universe), etc. This can only be done because those constants exists as such. In fact, the "hardest" sciences, such as Physics, are so because they have already established numerous constants on which to relay to progress science even further.

7. Correct. Although statistics can be, and are, used for other purposes than progress science, statistics are indeed based on the analysis of variability and related methods.

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Authors / Editors

JDPerezgonzalez

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