Scientific Studies key terms

A testable, falsifiable statement predicting how two or more variables relate, written before data collection so results can confirm or contradict it rather than being explained after the fact.

The factor a researcher deliberately changes or selects across treatment groups to observe whether it produces a change in the measured outcome.

The outcome that is measured or observed in an experiment; its value is expected to respond to changes in the factor the researcher manipulates.

A comparison group that receives no treatment or a neutral treatment, allowing researchers to separate the effect of the tested factor from other influences.

The group in a study that receives the treatment or condition being tested, whose results are compared against a baseline group.

An unmeasured factor that differs between groups and could plausibly explain the observed outcome, making the claimed cause uncertain.

Placing participants or samples into treatment groups by chance so that groups are similar on average and bias is reduced.

The number of observations or participants included in a study; larger samples generally produce more stable estimates and greater ability to detect real effects.

The consistency of a measurement or result when repeated under the same conditions; a reliable tool gives similar readings each time it is used.

The extent to which a measurement or study actually assesses or demonstrates what it claims to, rather than something related but different.

The difference between a recorded value and the true value, arising from instrument limits, human reading, or random fluctuation.

How closely repeated measurements of the same quantity agree with one another, regardless of whether they are close to the true value.

How close a measured or calculated value is to the true or accepted value of the quantity being determined.

A comparison of an experimental result to an accepted value, calculated as the absolute difference divided by the accepted value, then multiplied by one hundred.

The digits in a measurement that carry meaningful information about its precision, including all certain digits plus one estimated digit.

The arithmetic average of a data set, found by adding all values and dividing by the number of values; sensitive to extreme outliers.

The middle value of an ordered data set, or the average of the two middle values when the count is even; resistant to extreme outliers.

A measure of how spread out values are around the mean; a small value indicates clustered data and a large value indicates widely scattered data.

A data point that lies unusually far from the rest of the observations, possibly due to measurement error or a genuinely rare event.

A statistical relationship in which two variables tend to change together; it does not by itself establish that one causes the other.

A relationship in which a change in one factor directly produces a change in another, requiring controlled evidence rather than mere association.

A line fitted to plotted data that summarizes the overall direction of the relationship and can support predictions within the observed range.

Estimating values beyond the range of observed data by extending a trend; risky because the pattern may not continue outside measured conditions.

Estimating an unknown value that falls between two measured data points, generally more dependable than predicting beyond the measured range.

A result unlikely to have occurred by chance alone under the assumed null hypothesis, conventionally judged against a chosen probability threshold.

Evaluation of a study by independent experts in the field before publication, intended to catch flawed methods, unsupported claims, and errors.

The ability of independent researchers to obtain similar results by repeating a study with the same methods and comparable conditions.

A broad, well-tested explanation supported by extensive evidence that unifies many observations and predicts new findings; not a mere guess.

A concise statement, often mathematical, describing a consistent regularity observed in nature without explaining the underlying mechanism.

The principle that energy cannot be created or destroyed but only transferred between objects or transformed among forms, with total energy remaining constant.

The energy an object possesses because of its motion, increasing with both its mass and the square of its speed.

Stored energy that depends on an object's position or configuration, such as height in a gravitational field or stretch in a spring.

The principle that whenever one object exerts a force on a second, the second exerts an equal and opposite force on the first.

The tendency of an object to resist changes in its state of motion, proportional to its mass and described by Newton's first law.

A push or pull on an object that can change its motion or shape, measured in newtons and having both magnitude and direction.

The process by which individuals with inherited traits better suited to their environment tend to survive and reproduce more, shifting trait frequencies over generations.

An inherited characteristic that improves an organism's ability to survive and reproduce in its particular environment, arising through natural selection over many generations.

A change in the DNA sequence of a gene, which can alter traits and provides the raw variation on which evolutionary processes act.

The process by which plants, algae, and some bacteria convert light energy, water, and carbon dioxide into sugars, releasing oxygen as a byproduct.

The set of reactions by which cells release energy stored in sugars, using oxygen in aerobic forms and producing carbon dioxide and water.

A sequence showing how energy and matter pass from producers to consumers and decomposers through feeding relationships in an ecosystem.

The theory that Earth's rigid outer shell is broken into moving plates whose interactions at boundaries cause earthquakes, volcanoes, and mountain building.

The continuous series of processes by which igneous, sedimentary, and metamorphic rocks form, break down, and transform into one another over geologic time.

The transport of weathered rock and soil by moving water, wind, ice, or gravity from one location to another.

The warming of a planet's surface as certain atmospheric gases absorb and re-emit outgoing infrared radiation, trapping heat near the surface.

The fraction of incoming solar radiation reflected by a surface; bright surfaces such as ice reflect more and dark surfaces absorb more.

The long-term average pattern of temperature, precipitation, and other weather conditions in a region, typically assessed over decades.

A systematic comparison of the expected advantages and drawbacks of a technology or policy, often expressed in monetary or risk terms.

The process of estimating the likelihood and severity of harm from a hazard, used to inform decisions about technology and public safety.

The principles guiding honest, fair, and responsible conduct in research, including accurate reporting, humane treatment of subjects, and disclosure of conflicts.