> ## Documentation Index > Fetch the complete documentation index at: https://doc.lucidworks.com/llms.txt > Use this file to discover all available pages before exploring further. # Start an experiment > Activate the specified experiment. The response shows the experiment's properties, including `enabled=true`. ## OpenAPI ````yaml /api-reference/5.9/fusion-api-query.json post /experiments/{id}/job openapi: 3.0.1 info: title: Fusion Query API description: >- A Lucidworks Fusion microservice for machine-learning-enhanced ranking and retrieval. contact: name: Lucidworks url: www.lucidworks.com email: support@lucidworks.com license: name: License of API url: https://lucidworks.com/legal/developer-license-agreement/ version: '5.9' servers: - url: https://{FUSION HOST}/api description: Fusion variables: FUSION HOST: default: FUSION_HOST description: Your environment host. - url: https://{FUSION HOST}/api/apps/{APP_NAME} description: Fusion app variables: FUSION HOST: default: FUSION_HOST description: Your environment host. APP_NAME: default: APP_NAME description: The name of your Fusion app. security: - Basic auth: [] - API key: [] tags: - name: Custom Rule Type API description: Endpoints to define and manage custom rule type definitions. - name: Experiments API description: >- Use the Experiments API to compare different configuration variants and determine which ones are most successful. - name: Query Pipelines API description: >- Use these endpoints to view and manage your query pipelines. You can also send queries using this API, though the Query Profiles API is recommended instead. - name: Query Profiles API description: >- The Query Profiles API provides static endpoints that you can consistently point to when querying your collections. Query profiles allow you to change the query pipelines or collections behind them without changing the endpoint you use for your search queries. See the Query Profiles CRUD API for endpoints that create and modify query profiles. - name: Query Profiles CRUD API description: >- Use these endpoints to create and modify query profiles. Query profiles allow you to change the query pipelines or collections behind them without changing the endpoint you use for your search queries. See the Query Profiles API for the query endpoints. - name: Query Rewrite API description: >- The Query Rewrite API manages documents used for query rewriting to improve relevancy using AI-generated data. Primarily for internal use. - name: Query Stage API description: >- Use these endpoints to view the available query pipeline stages and their configuration parameters. - name: Query Stage Plugins API description: >- Use these endpoints to view, install, and manage custom query stages developed with the Query Stage SDK. - name: Signal Indexing API description: Endpoints to index signals. - name: Experience Manager API description: API only for internal use by the Experience Manager Springboard system - name: Query Pipeline Template API description: Used internally to generate query pipelines from a template. externalDocs: description: Lucidworks Documentation. url: https://doc.lucidworks.com/ paths: /experiments/{id}/job: post: tags: - Experiments API summary: Start an experiment description: >- Activate the specified experiment. The response shows the experiment's properties, including `enabled=true`. operationId: startJob parameters: - name: id description: The experiment ID. in: path required: true schema: type: string - name: ifMatch description: An optional tag to match. in: header required: false schema: $ref: '#/components/schemas/IfMatchHeader' responses: '200': description: OK content: '*/*': schema: $ref: '#/components/schemas/Experiment' components: schemas: IfMatchHeader: type: object Experiment: type: object properties: id: description: The experiment ID. type: string description: description: A description of this experiment. type: string uniqueIdParameter: description: The name of the request parameter containing the user ID. type: string baseSignalsCollection: description: >- Signals resulting from requests that flow through this experiment will go into the signal collection associated with this base collection. type: string variants: description: The variants belonging to this experiment. type: array items: $ref: '#/components/schemas/ExperimentVariant' automaticallyAdjustTraffic: description: >- `true` to enable multi-armed bandits; in that case, there is no need to specify a traffic weight for each variant. type: boolean enabled: description: '`True` if this experiment is enabled.' type: boolean startTimestamp: description: The date and time when the experiment was launched. type: string format: date-time runId: description: The experiment run ID. type: string metrics: description: Experiment metrics. type: array items: $ref: '#/components/schemas/ExperimentMetric' ExperimentVariant: type: object properties: id: description: The experiment variant ID. type: string name: description: The experiment variant name. type: string collection: description: The data collection associated with this experiment variant. type: string queryPipeline: description: The query pipeline associated with this experiment variant. type: string params: type: array items: $ref: '#/components/schemas/ParamAndValue' weight: description: This variant's traffic weight. type: number format: double ExperimentMetric: required: - type type: object properties: name: description: Experiment metric name. type: string description: description: Experiment metric description. type: string jobId: description: The job that produced this metric. type: string binary: type: boolean primary: type: boolean type: type: string discriminator: propertyName: type ParamAndValue: type: object properties: key: type: string value: type: string policy: type: string enum: - replace - append - remove - default securitySchemes: Basic auth: type: http scheme: basic API key: name: x-api-key type: apiKey in: header ````