Concept object

These are the original OpenAlex Concepts, which are being deprecated in favor of Topics. We will continue to provide these Concepts for Works, but we will not be actively maintaining, updating, or providing support for these concepts. Unless you have a good reason to be relying on them, we encourage you to look into Topics instead.

These are the fields in a concept object. When you use the API to get a single concept or lists of concepts, this is what's returned.

ancestors

List: List of concepts that this concept descends from, as dehydrated Concept objects. See the concept tree section for more details on how the different layers of concepts work together.

ancestors: [
    {
        id: "https://openalex.org/C2522767166",
        wikidata: "https://www.wikidata.org/wiki/Q2374463",
        display_name: "Data science",
        level: 1
    },
    {
        id: "https://openalex.org/C161191863",
        wikidata: "https://www.wikidata.org/wiki/Q199655",
        display_name: "Library science",
        level: 1
    },
    
    // and so forth
]

cited_by_count

Integer: The number citations to works that have been tagged with this concept. Or less formally: the number of citations to this concept.

For example, if there are just two works tagged with this concept and one of them has been cited 10 times, and the other has been cited 1 time, cited_by_count for this concept would be 11.

cited_by_count: 20248 

counts_by_year

List: The values of works_count and cited_by_count for each of the last ten years, binned by year. To put it another way: for every listed year, you can see how many new works were tagged with this concept, and how many times any work tagged with this concept got cited.

Years with zero citations and zero works have been removed so you will need to add those back in if you need them.

counts_by_year: [
    {
        year: 2021,
        works_count: 4211,
        cited_by_count: 120939
    },
    {
        year: 2020,
        works_count: 4363,
        cited_by_count: 119531
    },
    
    // and so forth
]

created_date

String: The date this Concept object was created in the OpenAlex dataset, expressed as an ISO 8601 date string.

created_date: "2017-08-08"

description

String: A brief description of this concept.

description: "study of alternative metrics for analyzing and informing scholarship"

display_name

String: The English-language label of the concept.

display_name: "Altmetrics"

id

String: The OpenAlex ID for this concept.

id: "https://openalex.org/C2778407487"

ids

Object: All the external identifiers that we know about for this concept. IDs are expressed as URIs whenever possible. Possible ID types:

• mag (Integer: this concept's Microsoft Academic Graph ID)

• openalex (String: this concept's OpenAlex ID. Same as Concept.id)

• umls_cui (List: this concept's Unified Medical Language System Concept Unique Identifiers)

• umls_aui (List: this concept's Unified Medical Language System Atom Unique Identifiers)

• wikidata (String: this concept's Wikidata ID. Same as Concept.wikidata)

• wikipedia (String: this concept's Wikipedia page URL)

Many concepts are missing one or more ID types (either because we don't know the ID, or because it was never assigned). Keys for null IDs are not displayed..

ids: {
    openalex: "https://openalex.org/C2778407487",
    wikidata: "https://www.wikidata.org/wiki/Q14565201",
    wikipedia: "https://en.wikipedia.org/wiki/Altmetrics",
    mag: 2778407487
}

image_thumbnail_url

String: Same as image_url, but it's a smaller image.

image_thumbnail_url: "https://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Altmetrics.svg/100px-Altmetrics.svg.png"

image_url

String: URL where you can get an image representing this concept, where available. Usually this is hosted on Wikipedia.

image_url: "https://upload.wikimedia.org/wikipedia/commons/f/f1/Altmetrics.svg"

international

Object: This concept's display name in many languages, derived from article titles on each language's wikipedia. See the Wikidata entry for "Java Bytecode" for example source data.

• display_name (Object)

  • key (String): language code in wikidata language code format. Full list of languages is here.

  • value (String): display_name in the given language

international: {
    display_name: {
        ca: "Altmetrics",
        ...
    }
}

level

Integer: The level in the concept tree where this concept lives. Lower-level concepts are more general, and higher-level concepts are more specific. Computer Science has a level of 0; Java Bytecode has a level of 5. Level 0 concepts have no ancestors and level 5 concepts have no descendants.

level: 2

related_concepts

List: Concepts that are similar to this one. Each listed concept is a dehydrated Concept object, with one additional attribute:

• score (Float): The strength of association between this concept and the listed concept, on a scale of 0-100.

related_concepts: [
    {
        id: "https://openalex.org/C2778793908",
        wikidata: null,
        display_name: "Citation impact",
        level: 3,
        score: 4.56749
    },
    {
        id: "https://openalex.org/C2779455604",
        wikidata: null,
        display_name: "Impact factor",
        level: 2,
        score: 4.46396
    }
    
    // and so forth
]

summary_stats

Object: Citation metrics for this concept

• 2yr_mean_citedness Float: The 2-year mean citedness for this source. Also known as impact factor. We use the year prior to the current year for the citations (the numerator) and the two years prior to that for the citation-receiving publications (the denominator).

• h_index Integer: The h-index for this concept.

• i10_index Integer: The i-10 index for this concept.

While the h-index and the i-10 index are normally author-level metrics and the 2-year mean citedness is normally a journal-level metric, they can be calculated for any set of papers, so we include them for concepts.

summary_stats: {
    2yr_mean_citedness: 1.5295340589458237,
    h_index: 105,
    i10_index: 5045
}

updated_date

String: The last time anything in this concept object changed, expressed as an ISO 8601 date string. This date is updated for any change at all, including increases in various counts.

updated_date: "2021-12-25T14:04:30.578837"

wikidata

String: The Wikidata ID for this concept. This is the Canonical External ID for concepts.

All OpenAlex concepts have a Wikidata ID, because all OpenAlex concepts are also Wikidata concepts.

wikidata: "https://www.wikidata.org/wiki/Q14565201"

works_api_url

String: An URL that will get you a list of all the works tagged with this concept.

We express this as an API URL (instead of just listing the works themselves) because there might be millions of works tagged with this concept, and that's too many to fit here.

works_api_url: "https://api.openalex.org/works?filter=concept.id:C2778407487"

works_count

Integer: The number of works tagged with this concept.

works_count: 3078 

The DehydratedConcept object

The DehydratedConcept is stripped-down Concept object, with most of its properties removed to save weight. Its only remaining properties are:

• [`display_name`](concept-object.md#display\_name)

• [`id`](concept-object.md#id)

• [`level`](concept-object.md#level)

• [`wikidata`](concept-object.md#wikidata)