{
  "id": 436501,
  "title": "Weighted Means Folly ?",
  "url": "/competitions/rsna-2023-abdominal-trauma-detection/discussion/436501",
  "author_name": "PC Jimmmy",
  "post_date": "2023-09-02T16:34:43.876000",
  "votes": 3,
  "comment_count": 1,
  "views": 0,
  "content": "<p>Most of the shared 'mean' notebooks are using weights that take the predictions what seems like a long way from the training means.</p>\n<p>For example, </p>\n<p><a href=\"https://www.kaggle.com/code/jasonheesanglee/rsna23-weighted-mean-baseline-57c31e\" target=\"_blank\">This one</a> seems to suggest that extravasation injuries will be 66% in the test set vs the mean from training of 6%.   </p>\n<p>One of the <a href=\"https://www.kaggle.com/code/vishakkbhat/rsna23-weighted-mean-baseline/output\" target=\"_blank\">early shared mean notebooks</a> had extravasation at 51% of the test set.</p>\n<p>Does anyone believe the test set will have such high levels of extravasation?</p>\n<p>I don't believe it - so does this mean that the metric has been poorly designed?   Or are we just chasing noise with weighted mean notebook submissions?</p>",
  "messages": [
    {
      "id": 2420498,
      "postDate": "2023-09-02T16:34:43.877Z",
      "content": "<p>Most of the shared 'mean' notebooks are using weights that take the predictions what seems like a long way from the training means.</p>\n<p>For example, </p>\n<p><a href=\"https://www.kaggle.com/code/jasonheesanglee/rsna23-weighted-mean-baseline-57c31e\" target=\"_blank\">This one</a> seems to suggest that extravasation injuries will be 66% in the test set vs the mean from training of 6%.   </p>\n<p>One of the <a href=\"https://www.kaggle.com/code/vishakkbhat/rsna23-weighted-mean-baseline/output\" target=\"_blank\">early shared mean notebooks</a> had extravasation at 51% of the test set.</p>\n<p>Does anyone believe the test set will have such high levels of extravasation?</p>\n<p>I don't believe it - so does this mean that the metric has been poorly designed?   Or are we just chasing noise with weighted mean notebook submissions?</p>",
      "rawMarkdown": "Most of the shared 'mean' notebooks are using weights that take the predictions what seems like a long way from the training means.\n\nFor example, \n\n[This one](https://www.kaggle.com/code/jasonheesanglee/rsna23-weighted-mean-baseline-57c31e) seems to suggest that extravasation injuries will be 66% in the test set vs the mean from training of 6%.   \n\nOne of the [early shared mean notebooks](https://www.kaggle.com/code/vishakkbhat/rsna23-weighted-mean-baseline/output) had extravasation at 51% of the test set.\n\nDoes anyone believe the test set will have such high levels of extravasation?\n\nI don't believe it - so does this mean that the metric has been poorly designed?   Or are we just chasing noise with weighted mean notebook submissions?\n\n",
      "votes": 3
    },
    {
      "id": 2428891,
      "postDate": "2023-09-08T08:24:57.670Z",
      "content": "<p>The optimal constant prediction (independently of all other targets) for <code>extravasation_injury</code>, given the training data, and given the weighted cross entropy metric, is approx 0.29 (with <code>extravasation_healthy</code> approx 0.71).</p>\n<p>What complicates matters is that the <code>any_injury</code> class is generated from the max of the (non-healthy) class predictions. If <code>extravasation_injury</code> is scaled up, then this will help contribute to the <code>any_injury</code> predictions (that class is 1 when <code>extravasation_injury</code> is 1 by definition).</p>\n<p>I don't know whether everyone attempting to parameter-tune the weighted mean to the public LB believes that there will be high levels of extravasation, but, up to a point it makes sense to scale it beyond its propensity.</p>",
      "rawMarkdown": "The optimal constant prediction (independently of all other targets) for `extravasation_injury`, given the training data, and given the weighted cross entropy metric, is approx 0.29 (with `extravasation_healthy` approx 0.71).\n\nWhat complicates matters is that the `any_injury` class is generated from the max of the (non-healthy) class predictions. If `extravasation_injury` is scaled up, then this will help contribute to the `any_injury` predictions (that class is 1 when `extravasation_injury` is 1 by definition).\n\nI don't know whether everyone attempting to parameter-tune the weighted mean to the public LB believes that there will be high levels of extravasation, but, up to a point it makes sense to scale it beyond its propensity."
    }
  ],
  "comments": [
    {
      "id": 2428891,
      "author_name": "jagofc",
      "author_url": "",
      "post_date": "2023-09-08T08:24:57.670000",
      "content": "<p>The optimal constant prediction (independently of all other targets) for <code>extravasation_injury</code>, given the training data, and given the weighted cross entropy metric, is approx 0.29 (with <code>extravasation_healthy</code> approx 0.71).</p>\n<p>What complicates matters is that the <code>any_injury</code> class is generated from the max of the (non-healthy) class predictions. If <code>extravasation_injury</code> is scaled up, then this will help contribute to the <code>any_injury</code> predictions (that class is 1 when <code>extravasation_injury</code> is 1 by definition).</p>\n<p>I don't know whether everyone attempting to parameter-tune the weighted mean to the public LB believes that there will be high levels of extravasation, but, up to a point it makes sense to scale it beyond its propensity.</p>",
      "votes": 0,
      "replies": []
    }
  ],
  "raw_markdown_by_id": {
    "2420498": "Most of the shared 'mean' notebooks are using weights that take the predictions what seems like a long way from the training means.\n\nFor example, \n\n[This one](https://www.kaggle.com/code/jasonheesanglee/rsna23-weighted-mean-baseline-57c31e) seems to suggest that extravasation injuries will be 66% in the test set vs the mean from training of 6%.   \n\nOne of the [early shared mean notebooks](https://www.kaggle.com/code/vishakkbhat/rsna23-weighted-mean-baseline/output) had extravasation at 51% of the test set.\n\nDoes anyone believe the test set will have such high levels of extravasation?\n\nI don't believe it - so does this mean that the metric has been poorly designed?   Or are we just chasing noise with weighted mean notebook submissions?\n\n",
    "2428891": "The optimal constant prediction (independently of all other targets) for `extravasation_injury`, given the training data, and given the weighted cross entropy metric, is approx 0.29 (with `extravasation_healthy` approx 0.71).\n\nWhat complicates matters is that the `any_injury` class is generated from the max of the (non-healthy) class predictions. If `extravasation_injury` is scaled up, then this will help contribute to the `any_injury` predictions (that class is 1 when `extravasation_injury` is 1 by definition).\n\nI don't know whether everyone attempting to parameter-tune the weighted mean to the public LB believes that there will be high levels of extravasation, but, up to a point it makes sense to scale it beyond its propensity."
  }
}