GLOSSARY
Research terms glossary
50 terms · Updated 2026-05-18
Clear, methodological definitions of terms frequently encountered in anxiety research, clinical trials, and epidemiological data.
Study design
- Randomized controlled trialA randomized controlled trial, often shortened to RCT, is a study that tests whether a treatment works by splitting people into groups at random. One group gets the treatment. Another group gets a comparison, such as a placebo or usual care.
- Systematic reviewA systematic review is a careful, organized summary of all the studies that have looked at the same question. It follows a written plan, so the process can be checked and repeated by someone else.
- Meta-analysisA meta-analysis is a math method that combines the results of several studies into one overall number. It often sits inside a systematic review.
- Network meta-analysisA network meta-analysis compares several treatments at once, including some that were never tested directly against each other in the same study.
- Cohort studyA cohort study follows a group of people over time to see what happens to them. It watches; it doesn't assign treatment.
- Cross-sectional studyA cross-sectional study takes a snapshot of a population at one moment in time. It measures things once, not over a stretch of time.
- Case-control studyA case-control study starts with the outcome. It compares people who already have a condition, the cases, with similar people who don't, the controls, then looks back to find differences.
- Intention-to-treat analysisIntention-to-treat means a trial counts every person in the group they were first assigned to, even if they stopped the treatment or dropped out partway through.
- Pragmatic trialA pragmatic trial tests a treatment in everyday conditions, with the kind of patients and clinics you'd see in normal care.
- BlindingBlinding means hiding who got which treatment, so that knowledge doesn't skew the results.
- Control groupThe control group is the comparison group in a study. It doesn't get the treatment being tested, so researchers have something to measure the treatment against.
- PlaceboA placebo is an inactive treatment, such as a sugar pill, used for comparison. It contains no active drug.
Statistics
- PrevalencePrevalence is the share of a population that has a condition at a given time. It answers the question "how many people have this."
- IncidenceIncidence is the rate at which new cases of a condition appear in a population over a period of time. It counts only the new cases.
- Odds ratioAn odds ratio compares the odds of an outcome in one group with the odds in another. It's a way to measure how strongly two things are linked.
- Relative riskRelative risk compares the chance of an outcome in one group with the chance in another. A relative risk of 1 means no difference.
- Hazard ratioA hazard ratio compares how quickly an outcome happens in one group versus another over time. It's about timing, not only whether something happens.
- Confidence intervalA confidence interval is a range of values that probably contains the true answer. It shows how precise a study's result is.
- p-valueA p-value is a number that tells you how surprising a result would be if the treatment actually did nothing. A small p-value means the result would be unlikely by chance alone.
- Statistical significanceA result is statistically significant when it's unlikely to be explained by chance alone. It is usually decided by a p-value below a set cutoff, often 0.05.
- Clinical significanceClinical significance asks whether a result is big enough to make a real difference to a patient's life. It is different from statistical significance.
- Effect sizeAn effect size is a number that describes how large a treatment's effect is. It lets you compare results across different studies and different measures.
- Number needed to treat (NNT)The number needed to treat, or NNT, is how many people would need to receive a treatment for one extra person to benefit.
- Number needed to harm (NNH)The number needed to harm, or NNH, is how many people would need to receive a treatment for one extra person to experience a particular harm, such as a side effect.
- HeterogeneityHeterogeneity is the amount that study results differ from each other when they're combined in a meta-analysis. High heterogeneity means the studies disagreed.
- Minimal clinically important differenceThe minimal clinically important difference, or MCID, is the smallest change on a symptom scale that a patient would actually notice and consider meaningful.
- Dose-responseA dose-response relationship means that more of something is linked to more of an effect. As the dose goes up, the response changes in step.
Clinical outcomes
- ComorbidityComorbidity means having two or more health conditions at the same time.
- RemissionRemission means a condition's symptoms have dropped low enough that the person no longer meets the criteria for the diagnosis. The condition is quiet, though not necessarily gone for good.
- Response rateThe response rate is the share of people in a study who improved by a set amount, often a 50 percent drop in symptoms.
- RelapseRelapse is the return of a condition's symptoms after a period of improvement or remission.
- Treatment adherenceTreatment adherence is how closely a person follows a treatment as it was planned, such as taking a medication regularly or attending therapy sessions.
- DropoutDropout is when a participant leaves a study before it ends, or a patient stops a treatment before completing it.
- Discontinuation syndromeDiscontinuation syndrome is a set of symptoms that can appear when a person stops or quickly lowers an antidepressant, such as an SSRI or SNRI.
- Sustained responseA sustained response means an improvement that holds up over time, rather than fading after a few weeks.
- Patient-reported outcomeA patient-reported outcome is a result measured by what the patient says about their own health, rather than by a lab test or a clinician's rating.
Treatment research
- Generalized anxiety disorderA chronic condition characterized by excessive, uncontrollable worry about everyday issues.
- Social anxiety disorderAn intense, persistent fear of being watched and judged by others in social situations.
- Cognitive behavioral therapyCognitive behavioral therapy, or CBT, is a structured, time-limited talk therapy. It works on the links between thoughts, feelings, and behavior.
- Exposure therapyA behavioral treatment in which patients repeatedly and systematically engage with feared stimuli, situations, or sensations to weaken fear responses.
- Interoceptive exposureInteroceptive exposure is a CBT technique that has a person bring on the body sensations they fear, on purpose and in a safe setting, so those sensations feel less threatening over time.
- SSRIAn SSRI, or selective serotonin reuptake inhibitor, is a class of antidepressant medication. SSRIs are also a first-line medication for most adult anxiety disorders.
- SNRIAn SNRI, or serotonin-norepinephrine reuptake inhibitor, is a class of antidepressant medication. SNRIs are also used as a first-line medication for several anxiety disorders.
- BenzodiazepineA benzodiazepine is a class of medication that calms the nervous system quickly. Benzodiazepines reduce acute anxiety fast, but long-term use carries real risks.
Conditions
- Panic disorderPanic disorder is an anxiety disorder marked by repeated, unexpected panic attacks and ongoing worry about having more of them.
Tools and instruments
- Screening toolA screening tool is a short, standardized questionnaire that flags whether a person may have a condition and should be assessed further. It doesn't make a diagnosis.
- GAD-7The GAD-7 is a short, seven-question form used to screen for and measure generalized anxiety. The letters stand for Generalized Anxiety Disorder 7-item scale.
- PHQ-9The PHQ-9 is a short, nine-question form used to screen for and measure depression. The letters stand for Patient Health Questionnaire 9-item scale.
- DSM-5-TRThe DSM-5-TR is the handbook US clinicians use to name and define mental health conditions. The letters stand for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision.
- ICD-11The ICD-11 is the global system for classifying diseases and health conditions, including mental health conditions. ICD stands for International Classification of Diseases, and 11 is the current edition.