science

GADM

GADM 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 GADM rather than just read about it. In short: GADM, the Database of Global Administrative Areas, is a high-resolution database of country administrative areas, with a goal of "all countries, at all levels, at any time period." Although it is a public database, GADM has a higher spatial resolution than other free databases, and also higher than commercial software such as ArcGIS. Those sources are commonly use to complete data analysis with data visualisation su…

Key takeaways

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

Reference excerpt

GADM, the Database of Global Administrative Areas, is a high-resolution database of country administrative areas, with a goal of "all countries, at all levels, at any time period." Although it is a public database, GADM has a higher spatial resolution than other free databases, and also higher than commercial software such as ArcGIS. Those sources are commonly use to complete data analysis with data visualisation such as data plots, choropleth map, etc.

Format The database is available in a few export formats, including shapefiles that are used in most common GIS applications. Files for use with the data analysis language R are also available.

License GADM is not freely available for commercial use. The GADM project created the spatial data for many countries from spatial databases provided by national governments, NGO, and/or from maps and lists of names available on the Internet (e.g. from Wikipedia).

Illustrations

Worked examples

Example 1 — a first encounter with GADM

Start with the simplest possible case. Write down what GADM 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 GADM 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 GADM 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 GADM

In research: GADM 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 GADM 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: GADM is common in secondary-school and first-year university syllabi. It links to neighbouring topics Collaborative mapping, Geographical databases, Web mapping, so understanding it makes those chapters shorter.
In everyday life: Look for GADM 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 GADM in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GADM 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 GADM out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GADM in simple terms?

Why does GADM 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 GADM?

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 GADM.