{
  "category": "Statistical functions",
  "display_name": "FORECAST.ETS.SEASONALITY",
  "entry_kind": "built_in_function",
  "eval_api": {
    "method": "POST",
    "url": "https://handbook.dnacalc.com/api/eval"
  },
  "function_id": "FUNC.FORECAST.ETS.SEASONALITY",
  "implementation_state": {
    "answer_bank": null,
    "detail": "Listed by Microsoft; no catalogue row yet.",
    "dnacalc_commit": "9e1884369a678158dd82d3d74188daf986995e87",
    "in_catalogue": false,
    "state": "refuses",
    "state_label": "Refuses or not implemented",
    "summary": "Not implemented",
    "workbook_corpus": null
  },
  "implementations": [],
  "json_url": "https://handbook.dnacalc.com/api/functions/FUNC.FORECAST.ETS.SEASONALITY.json",
  "name": "FORECAST.ETS.SEASONALITY",
  "notes": [],
  "schema": "efh.function-reference/v1",
  "section_order": [
    "what-it-does",
    "try-it",
    "quirks",
    "how-to-implement",
    "version-differences",
    "alternatives"
  ],
  "sections": {
    "alternatives": "\n- `FORECAST.LINEAR` for a straight-line forecast.\n- `TREND` and `GROWTH` for fitted series.\n- The Forecast Sheet command, which builds on the same family.\n\n\n",
    "how-to-implement": "\nNo implementation exists yet. It needs the AAA exponential smoothing fit, the detection of a constant timeline step, seasonality\ndetection, the data-completion and aggregation rules, and recorded Excel answers to fix the optimiser's stopping\nrules. Forecast values depend on those rules, so they must be measured and not assumed.\n\n\n",
    "quirks": "\nThe timeline, data-completion and aggregation rules follow [FORECAST.ETS](FUNC.FORECAST.ETS.md).\n\n\n",
    "sources": "\n- [FORECAST.ETS.SEASONALITY function](https://support.microsoft.com/en-us/excel/functions/forecast-ets-seasonality-function)\n- [FORECAST.ETS function](https://support.microsoft.com/en-us/excel/functions/forecast-ets-function)\n\n",
    "version-differences": "\nMicrosoft says these functions are not available in Excel for the web, iOS or Android. No Excel answers for this function are recorded here, so no comparison between Excel builds exists.\n\n\n",
    "what-it-does": "\n`FORECAST.ETS.SEASONALITY` returns the length of the repeating pattern that exponential smoothing detects in a timed series.\n\n`FORECAST.ETS.SEASONALITY(values, timeline, [data_completion], [aggregation])`\n\nUse it to see what `FORECAST.ETS` would detect by default, or to set `seasonality` explicitly.\n\n\n"
  },
  "signature": {
    "display": "FORECAST.ETS.SEASONALITY(values, timeline, [data_completion], [aggregation])",
    "parameters": [
      {
        "description": null,
        "name": "values",
        "optional": false,
        "repeats": false
      },
      {
        "description": null,
        "name": "timeline",
        "optional": false,
        "repeats": false
      },
      {
        "description": null,
        "name": "data_completion",
        "optional": true,
        "repeats": false
      },
      {
        "description": null,
        "name": "aggregation",
        "optional": true,
        "repeats": false
      }
    ],
    "trailing_repeats": false
  },
  "sources": {
    "metadata": {
      "admission": {
        "label": "not_implemented",
        "reason": "Listed by Microsoft; no catalogue row yet."
      },
      "arity": {
        "max": 4,
        "min": 2
      },
      "category": "Statistical functions",
      "classification": {},
      "descriptions": {
        "long": null,
        "short": "Length of the repeating pattern found in a time series",
        "short_source": "dna-calc-own"
      },
      "docs": {
        "english_description": null,
        "microsoft_url": "https://support.microsoft.com/en-us/excel/functions/forecast-ets-seasonality-function"
      },
      "entry_kind": "built_in_function",
      "localized_family_names": null,
      "localized_names": [],
      "signature": {
        "display": "FORECAST.ETS.SEASONALITY(values, timeline, [data_completion], [aggregation])",
        "parameters": [
          {
            "description": null,
            "name": "values",
            "optional": false,
            "repeats": false
          },
          {
            "description": null,
            "name": "timeline",
            "optional": false,
            "repeats": false
          },
          {
            "description": null,
            "name": "data_completion",
            "optional": true,
            "repeats": false
          },
          {
            "description": null,
            "name": "aggregation",
            "optional": true,
            "repeats": false
          }
        ],
        "trailing_repeats": false
      },
      "surface_name": "FORECAST.ETS.SEASONALITY",
      "version_marker": null,
      "xlcall": null
    },
    "microsoft": "https://support.microsoft.com/en-us/excel/functions/forecast-ets-seasonality-function"
  },
  "try_it": {
    "formula": "=FORECAST.ETS.SEASONALITY({1,2,3,4,5},{1,2,3,4,5})",
    "note": "The OneCalc preview has no answer for this function: see the state above.",
    "preview_status": "worksheet-error"
  },
  "url": "https://handbook.dnacalc.com/functions/FORECAST.ETS.SEASONALITY.html",
  "variants": [],
  "versions": []
}