hypothesisnoun
hy-POTH-uh-sis
A proposed explanation for an observation, made as a starting point for further investigation. A hypothesis must be testable — it needs to make predictions that can be checked against real-world evidence.
"Their hypothesis was that sleep deprivation impairs decision-making — a testable claim they set out to investigate systematically."
theorynoun
THEE-uh-ree
In science, a well-substantiated explanation of a natural phenomenon, supported by extensive evidence and repeatedly tested. A scientific theory is not a guess — it is the highest level of explanation in science, far more than an everyday "theory."
"Evolution is not 'just a theory' in the casual sense — it is a scientific theory backed by overwhelming evidence from multiple fields."
evidencenoun
EV-ih-dunts
Facts, observations, or data that indicate whether a belief or proposition is true or false. In science, evidence must be independently verifiable — not just reported, but reproducible by others.
"The evidence for the link between smoking and lung cancer built up slowly over decades, from multiple independent studies."
experimentnoun
ik-SPAIR-ih-munt
A controlled procedure carried out to test a hypothesis, discover a fact, or demonstrate a known fact. Experiments isolate variables to establish cause-and-effect relationships that observation alone cannot reveal.
"The experiment used a control group and a treatment group to isolate the effect of the new drug from the placebo effect."
peer reviewnoun phrase
peer rih-VYOO
The process by which a scientific paper is evaluated by independent experts in the same field before publication. Peer review is not infallible, but it is the primary mechanism by which science self-corrects and maintains standards.
"The study had not yet passed peer review, so its dramatic findings should be treated with caution until other experts had scrutinized the methods."
replicationnoun
rep-lih-KAY-shun
The ability to repeat an experiment and obtain the same results. Replication is fundamental to science — a finding that cannot be replicated by independent researchers is unreliable, no matter how dramatic it seems.
"The replication crisis revealed that many celebrated findings in psychology failed to hold up when other labs tried to reproduce them."
falsifiableadjective
FAWL-sih-fy-uh-bul
Capable of being proven wrong by an observation or experiment; able to be tested and potentially refuted. Karl Popper argued that falsifiability is the key criterion distinguishing genuine scientific claims from pseudoscience.
"'All swans are white' is falsifiable — you only need to find one black swan to disprove it. Many conspiracy theories are not falsifiable."
empiricaladjective
em-PEER-ih-kul
Based on observation or experience rather than theory or pure logic. Empirical claims are those that can in principle be tested against reality through observation or experiment.
"The question of whether meditation reduces anxiety is an empirical one — we can study it systematically and measure the outcomes."
observationnoun
ob-zur-VAY-shun
The act of carefully watching, measuring, or noticing facts about the world as a basis for scientific inquiry. Scientific observation differs from casual noticing — it is systematic, recorded, and designed to minimize observer bias.
"Darwin's theory of natural selection grew out of years of careful observation of animal populations across multiple continents."
datanoun (plural)
DAY-tuh
Facts and statistics collected for reference or analysis; the raw material of scientific investigation. Data must be interpreted carefully — the same data set can often support more than one conclusion.
"The data clearly showed a correlation between screen time and sleep disruption, though the direction of causation was less clear."
variablenoun
VAIR-ee-uh-bul
A factor that can change or be changed in an experiment. Identifying and controlling variables is essential for valid experimental results. The independent variable is what is manipulated; the dependent variable is what is measured.
"The key variable they failed to control for was income — wealthier participants consistently performed better, skewing all the results."
correlationnoun
kor-uh-LAY-shun
A statistical relationship between two variables — when one changes, the other tends to change too. Correlation does not establish causation: two things can move together without one causing the other.
"There is a strong correlation between ice cream sales and drowning rates, but ice cream does not cause drowning — both rise in summer heat."
causationnoun
kaw-ZAY-shun
The relationship in which one event or condition directly produces another. Establishing causation requires more than correlation — it requires controlled experiments or strong causal reasoning that rules out alternative explanations.
"Proving causation between a lifestyle factor and a disease is far harder than showing correlation — and yet causation is what really matters for treatment."
consensusnoun
kun-SEN-sus
A general agreement among a group, especially among scientists in a field based on shared evaluation of the evidence. Scientific consensus is not infallible, but it represents the collective judgment of those best positioned to evaluate the evidence.
"There is strong scientific consensus that human activity is driving climate change — a fact that is sometimes obscured by media coverage presenting it as a debate."
methodologynoun
meth-uh-DOL-uh-jee
The system of methods and principles used in a particular field of study or activity. In science, methodology describes how a study was designed and conducted — flawed methodology can invalidate even interesting findings.
"Critics of the study questioned the methodology: the survey relied on self-reported behavior, which is notoriously unreliable."
sample sizenoun phrase
SAM-pul syz
The number of individuals or units included in a study. Small sample sizes produce unreliable results that may not generalize to the broader population. Large, well-selected samples are essential for statistically meaningful findings.
"The study's conclusions were hard to trust — a sample size of twelve people is simply too small to support such sweeping claims."
controlledadjective
kun-TROHLD
Describes an experiment in which all variables except the one being tested are kept constant, allowing researchers to isolate the effect of that single variable. A controlled experiment is the gold standard for establishing causation.
"A controlled trial is essential — without one, we cannot know whether the improvement was caused by the treatment or by some other factor."
placebonoun
pluh-SEE-boh
An inactive treatment given to a control group to compare against a real treatment. The placebo effect — in which patients improve simply because they believe they are being treated — must be accounted for in any medical trial.
"The placebo group also showed improvement, which meant the researchers had to determine whether the drug did anything beyond what belief alone could achieve."
double-blindadjective
DUB-ul-blynd
Describes a study in which neither the participants nor the researchers evaluating outcomes know who received the real treatment and who received the placebo. Double-blind design eliminates both participant expectation and researcher bias.
"The double-blind design was essential: if the doctors knew which patients had the drug, their assessments might unconsciously favor the treatment group."
outliernoun
OWT-ly-ur
A data point that differs significantly from the pattern shown by most other data points. Outliers may indicate measurement errors, genuinely unusual cases, or important exceptions that challenge the general rule.
"One participant's results were such an outlier that the team had to decide whether to include or exclude the data before drawing conclusions."
anomalynoun
uh-NOM-uh-lee
Something that deviates from the expected or normal pattern; an observation that doesn't fit the existing theory. Anomalies are important in science — they often point toward the need for a new or revised explanation.
"The anomaly in the data — a result that should have been impossible under the current model — prompted a full review of their assumptions."
paradigmnoun
PAIR-uh-dym
The dominant framework of assumptions, methods, and standards within a scientific discipline at a given time. As described by Thomas Kuhn, normal science operates within a paradigm — until anomalies accumulate and force a revolution.
"For decades, the germ theory of disease was not the reigning paradigm — doctors resisted accepting that invisible microbes could cause illness."
scientific methodnoun phrase
sy-un-TIF-ik METH-ud
The systematic process of generating knowledge through observation, hypothesis, experimentation, and revision. The scientific method is not a rigid formula but a set of principles designed to minimize bias and error in the pursuit of reliable knowledge.
"The scientific method's power comes not from being infallible, but from being self-correcting — errors are eventually exposed and corrected."
publication biasnoun phrase
pub-lih-KAY-shun BY-us
The tendency for journals to publish studies with positive or dramatic results while rejecting null results. Publication bias distorts the scientific record and makes treatments appear more effective than they actually are.
"Publication bias means that for every exciting finding you read about, there may be a dozen failed replications sitting unpublished in researchers' files."
meta-analysisnoun
MEH-tuh uh-NAL-ih-sis
A statistical analysis that combines and synthesizes the results of multiple independent studies on the same question. Meta-analyzes are considered the strongest form of evidence because they aggregate data across many studies, reducing the impact of any single flawed study.
"The meta-analysis of over fifty trials gave a much more reliable picture of the drug's effectiveness than any single study could provide."