{
  "id": 69472,
  "title": "Sum of probabilities be unity or not?",
  "url": "/competitions/PLAsTiCC-2018/discussion/69472",
  "author_name": "",
  "post_date": "2018-10-24T02:19:02.925890500Z",
  "votes": 1,
  "comment_count": 2,
  "views": 0,
  "content": "<p>Hi folks!</p>\n\n<p>Had a question.</p>\n\n<p>The data_note.pdf states in section 3.1 that \"Participants will be required to submit a matrix of probabilistic classifications: a table with 3:5 million rows and 15 columns (the 14 already seen in the training data and one others class), <strong>where the sum of probabilities across all classes per row (object) <em>is unity.</em></strong>\"</p>\n\n<p>While the Evaluation section on kaggle.com (<a href=\"https://www.kaggle.com/c/PLAsTiCC-2018#evaluation\">https://www.kaggle.com/c/PLAsTiCC-2018#evaluation</a>) states that \"<strong>The submitted probabilities for a given object are <em>not</em> required to sum to one</strong> because they are rescaled prior to being scored (each row is divided by the row sum).\"</p>\n\n<p>So should the sum be unity or not? Or did I misread something?</p>",
  "messages": [
    {
      "id": "409256",
      "postDate": "10/24/2018 02:19:02",
      "content": "<p>Hi folks!</p>\n\n<p>Had a question.</p>\n\n<p>The data_note.pdf states in section 3.1 that \"Participants will be required to submit a matrix of probabilistic classifications: a table with 3:5 million rows and 15 columns (the 14 already seen in the training data and one others class), <strong>where the sum of probabilities across all classes per row (object) <em>is unity.</em></strong>\"</p>\n\n<p>While the Evaluation section on kaggle.com (<a href=\"https://www.kaggle.com/c/PLAsTiCC-2018#evaluation\">https://www.kaggle.com/c/PLAsTiCC-2018#evaluation</a>) states that \"<strong>The submitted probabilities for a given object are <em>not</em> required to sum to one</strong> because they are rescaled prior to being scored (each row is divided by the row sum).\"</p>\n\n<p>So should the sum be unity or not? Or did I misread something?</p>",
      "rawMarkdown": "Hi folks!\n\nHad a question.\n\nThe data_note.pdf states in section 3.1 that \"Participants will be required to submit a matrix of probabilistic classifications: a table with 3:5 million rows and 15 columns (the 14 already seen in the training data and one others class), **where the sum of probabilities across all classes per row (object) *is unity.***\"\n\nWhile the Evaluation section on kaggle.com (https://www.kaggle.com/c/PLAsTiCC-2018#evaluation) states that \"**The submitted probabilities for a given object are *not* required to sum to one** because they are rescaled prior to being scored (each row is divided by the row sum).\"\n\nSo should the sum be unity or not? Or did I misread something?",
      "votes": null
    },
    {
      "id": "409260",
      "postDate": "10/24/2018 02:33:43",
      "content": "<p>Apologies for the confusion. The sum of your probabilities <em>should</em> be unity, but if that's not the case then the evaluation metric will effectively rescale your probabilities until they do sum to unity.</p>",
      "rawMarkdown": "Apologies for the confusion. The sum of your probabilities *should* be unity, but if that's not the case then the evaluation metric will effectively rescale your probabilities until they do sum to unity.",
      "votes": null
    },
    {
      "id": "409534",
      "postDate": "10/24/2018 13:00:14",
      "content": "<p>Thank you for the clarification!</p>",
      "rawMarkdown": "Thank you for the clarification!",
      "votes": null
    }
  ],
  "comments": [
    {
      "id": 409260,
      "author_name": "sohier",
      "author_url": "",
      "post_date": "10/24/2018 02:33:43",
      "content": "<p>Apologies for the confusion. The sum of your probabilities <em>should</em> be unity, but if that's not the case then the evaluation metric will effectively rescale your probabilities until they do sum to unity.</p>",
      "votes": null,
      "replies": []
    },
    {
      "id": 409534,
      "author_name": "lenoyjacob",
      "author_url": "",
      "post_date": "10/24/2018 13:00:14",
      "content": "<p>Thank you for the clarification!</p>",
      "votes": null,
      "replies": []
    }
  ],
  "raw_markdown_by_id": {
    "409256": "Hi folks!\n\nHad a question.\n\nThe data_note.pdf states in section 3.1 that \"Participants will be required to submit a matrix of probabilistic classifications: a table with 3:5 million rows and 15 columns (the 14 already seen in the training data and one others class), **where the sum of probabilities across all classes per row (object) *is unity.***\"\n\nWhile the Evaluation section on kaggle.com (https://www.kaggle.com/c/PLAsTiCC-2018#evaluation) states that \"**The submitted probabilities for a given object are *not* required to sum to one** because they are rescaled prior to being scored (each row is divided by the row sum).\"\n\nSo should the sum be unity or not? Or did I misread something?",
    "409260": "Apologies for the confusion. The sum of your probabilities *should* be unity, but if that's not the case then the evaluation metric will effectively rescale your probabilities until they do sum to unity.",
    "409534": "Thank you for the clarification!"
  },
  "source": "meta"
}