science

Prospective cohort study

Prospective cohort study is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Prospective cohort study rather than just read about it. In short: A prospective cohort study is a longitudinal cohort study that follows over time a group of similar individuals (cohorts) who differ with respect to certain factors under study to determine how these factors affect rates of a certain outcome. For example, one might follow a cohort of middle-aged truck drivers who vary in terms of smoking habits to test the hypothesis that the 20-year incidence rate of lung cancer wi…

Key takeaways

Prospective cohort study belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Prospective cohort study to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Prospective cohort study from memory before moving on to harder problems.

Reference excerpt

A prospective cohort study is a longitudinal cohort study that follows over time a group of similar individuals (cohorts) who differ with respect to certain factors under study to determine how these factors affect rates of a certain outcome. For example, one might follow a cohort of middle-aged truck drivers who vary in terms of smoking habits to test the hypothesis that the 20-year incidence rate of lung cancer will be highest among heavy smokers, followed by moderate smokers, and then non–smokers. The prospective study is important for research on the etiology of diseases and disorders. The distinguishing feature of a prospective cohort study is that at the time the investigators begin enrolling subjects and collecting baseline exposure information, none of the subjects have developed any of the outcomes of interest. After baseline information is collected, subjects in a prospective cohort study are then followed "longitudinally," i.e., over a period of time, usually for years, to determine if and when they become diseased and whether their exposure status changes outcomes. In this way, investigators can eventually use the data to answer many questions about the associations between "risk factors" and disease outcomes. For example, one could identify smokers and non-smokers at baseline and compare their subsequent incidence of developing heart disease. Alternatively, one could group subjects based on their body mass index (BMI) and compare their risk of developing heart disease or cancer. Prospective cohort studies are typically ranked higher in the hierarchy of evidence than retrospective cohort studies and can be more expensive than a case–control study. One of the advantages of prospective cohort studies is that they can help determine risk factors for being infected with a new disease because they are a longitudinal observation over time, and the collection of results is at regular time intervals, so recall error is minimized.

Reporting The Strengthening the Reporting of Observational studies in Epidemiology (STROBE) recommends that authors refrain from calling a study ‘prospective’ or ‘retrospective’ due to these terms having contradictory and overlapping definitions. STROBE also recommends that whenever authors use these words, they specify which definition they use, including a detailed description of how and when data collection took place.

Examples Caerphilly Heart Disease Study, UK. Canadian Longitudinal Study on Aging / Étude longitudinale canadienne sur le vieillissement (CLSA-ÉLCV) The CARTaGENE cohort / Quebec's largest prospective study , Quebec, Canada Cebu Longitudinal Health and Nutrition Survey, the Philippines Framingham Heart Study, USA. LifE Study, Germany. Million Women Study, UK. Rotterdam Study, Netherlands. Tsimane’ Amazonian Panel Study, Bolivia The UK biobank , UK

See also Retrospective cohort study Blinded experiment Clinical trial Therapeutic effect Randomization

References

This article incorporates public domain material from Dictionary of Cancer Terms. U.S. National Cancer Institute.

Illustrations

Worked examples

Example 1 — a first encounter with Prospective cohort study

Start with the simplest possible case. Write down what Prospective cohort study claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Prospective cohort study before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Prospective cohort study ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Prospective cohort study

In research: Prospective cohort study appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Prospective cohort study in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Prospective cohort study is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cohort study methods, so understanding it makes those chapters shorter.
In everyday life: Look for Prospective cohort study outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Prospective cohort study in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Prospective cohort study means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Prospective cohort study out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Prospective cohort study in simple terms?

Why does Prospective cohort study matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Prospective cohort study?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Prospective cohort study.