Glossary
Causation
A relationship where a change in one variable directly produces a change in another variable, indicating a cause-and-effect link.
Example:
In a controlled experiment, if a new fertilizer is applied to plants and they consistently grow taller than plants without it, this demonstrates causation between the fertilizer and plant height.
Confounding variables
An unmeasured third variable that influences both the explanatory and response variables, creating an apparent association that is not a direct causal link.
Example:
If a study finds a positive correlation between shoe size and reading ability in children, age is a likely confounding variable because older children have larger feet and better reading skills.
Correlation
A statistical measure that quantifies the strength and direction of the linear association between two quantitative variables.
Example:
A strong positive correlation between daily ice cream sales and temperature suggests that as the temperature rises, ice cream sales also tend to increase.
Large sample size
Collecting data from a sufficiently great number of individuals or observations to ensure that the results are statistically reliable and representative of the broader population.
Example:
To accurately estimate the average screen time of teenagers, researchers would need a large sample size of hundreds or thousands of teens, not just a handful from one school.
Linear relationships
A pattern observed in a scatterplot where the data points tend to follow a straight line, indicating a consistent rate of change between two variables.
Example:
When plotting the number of hours a student studies against their exam score, a linear relationship might show that for every additional hour studied, the score increases by a consistent amount.
Random Error
Unpredictable and uncontrollable variations in measurements that cause data points to scatter around the true value, often due to natural variability or measurement imprecision.
Example:
When repeatedly weighing an object on a digital scale, slight fluctuations in the last decimal place due to air currents or minor vibrations are examples of random error.
Repeat study
The process of conducting a research study multiple times, often in different populations or under varied conditions, to verify the consistency and generalizability of the findings.
Example:
Before a new educational program is widely adopted, educators might repeat study trials in diverse school districts to confirm its effectiveness across different student demographics.
Systematic Error
A consistent and predictable error in measurement that causes readings to deviate from the true value in a specific direction, often due to a flaw in the instrument or method.
Example:
If a thermometer consistently reads 2 degrees Celsius higher than the actual temperature, every measurement taken with that thermometer will have a systematic error of +2°C.