{
  "id": 668808,
  "title": "CV over LB",
  "url": "/competitions/csiro-biomass/discussion/668808",
  "author_name": "",
  "post_date": "2026-01-19T06:10:06.200479400Z",
  "votes": -8,
  "comment_count": 4,
  "views": 0,
  "content": "<p>In competitions with small datasets (like this one with ~350 unique training images), the Public LB is calculated on maybe 20-30% of the test data. That means the leaderboard score is based on just ~50-100 images.\nIf you tune your model to improve the LB score on those 50 images, you are overfitting the leaderboard.\nWhen the Private LB (the other 70%) is revealed at the end, models that chased the Public LB usually crash. Models with robust CV rise to the top.</p>\n<p>Thus, I think we need to focus on improving CV</p>",
  "messages": [
    {
      "id": "3393490",
      "postDate": "01/19/2026 06:10:06",
      "content": "<p>In competitions with small datasets (like this one with ~350 unique training images), the Public LB is calculated on maybe 20-30% of the test data. That means the leaderboard score is based on just ~50-100 images.\nIf you tune your model to improve the LB score on those 50 images, you are overfitting the leaderboard.\nWhen the Private LB (the other 70%) is revealed at the end, models that chased the Public LB usually crash. Models with robust CV rise to the top.</p>\n<p>Thus, I think we need to focus on improving CV</p>",
      "rawMarkdown": "In competitions with small datasets (like this one with ~350 unique training images), the Public LB is calculated on maybe 20-30% of the test data. That means the leaderboard score is based on just ~50-100 images.\nIf you tune your model to improve the LB score on those 50 images, you are overfitting the leaderboard.\nWhen the Private LB (the other 70%) is revealed at the end, models that chased the Public LB usually crash. Models with robust CV rise to the top.\n\nThus, I think we need to focus on improving CV",
      "votes": null
    },
    {
      "id": "3393492",
      "postDate": "01/19/2026 06:13:02",
      "content": "<p><img src=\"https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F8a809d9e8c4d657c631db295afda0c25%2FScreenshot%202026-01-19%20at%2013.11.14.png?generation=1768803103667605&amp;alt=media\" alt=\"\">\n<img src=\"https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F5e22a1b48e1d7d4b40352110ff1e24c0%2FScreenshot%202026-01-19%20at%2013.12.21.png?generation=1768803174037558&amp;alt=media\" alt=\"\"></p>",
      "rawMarkdown": "![](https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F8a809d9e8c4d657c631db295afda0c25%2FScreenshot%202026-01-19%20at%2013.11.14.png?generation=1768803103667605&alt=media)\n![](https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F5e22a1b48e1d7d4b40352110ff1e24c0%2FScreenshot%202026-01-19%20at%2013.12.21.png?generation=1768803174037558&alt=media)",
      "votes": null
    },
    {
      "id": "3393731",
      "postDate": "01/19/2026 17:02:34",
      "content": "<p>I think that LB is more important. CV seems to be a bit leaky. </p>",
      "rawMarkdown": "I think that LB is more important. CV seems to be a bit leaky.",
      "votes": null
    },
    {
      "id": "3393747",
      "postDate": "01/19/2026 17:36:56",
      "content": "<p>Yeah, you are right, I neglected the info. But I think both 357 and 800 images are few to build better model that generalizes well.</p>",
      "rawMarkdown": "Yeah, you are right, I neglected the info. But I think both 357 and 800 images are few to build better model that generalizes well.",
      "votes": null
    },
    {
      "id": "3393748",
      "postDate": "01/19/2026 17:37:45",
      "content": "<p>You should watch out for the leakage.</p>",
      "rawMarkdown": "You should watch out for the leakage.",
      "votes": null
    }
  ],
  "comments": [
    {
      "id": 3393492,
      "author_name": "quan0095",
      "author_url": "",
      "post_date": "01/19/2026 06:13:02",
      "content": "<p><img src=\"https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F8a809d9e8c4d657c631db295afda0c25%2FScreenshot%202026-01-19%20at%2013.11.14.png?generation=1768803103667605&amp;alt=media\" alt=\"\">\n<img src=\"https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F5e22a1b48e1d7d4b40352110ff1e24c0%2FScreenshot%202026-01-19%20at%2013.12.21.png?generation=1768803174037558&amp;alt=media\" alt=\"\"></p>",
      "votes": null,
      "replies": [
        {
          "id": 3393747,
          "author_name": "ibratusmonov",
          "author_url": "",
          "post_date": "01/19/2026 17:36:56",
          "content": "<p>Yeah, you are right, I neglected the info. But I think both 357 and 800 images are few to build better model that generalizes well.</p>",
          "votes": null,
          "replies": []
        }
      ]
    },
    {
      "id": 3393731,
      "author_name": "jankowalski2000",
      "author_url": "",
      "post_date": "01/19/2026 17:02:34",
      "content": "<p>I think that LB is more important. CV seems to be a bit leaky. </p>",
      "votes": null,
      "replies": [
        {
          "id": 3393748,
          "author_name": "ibratusmonov",
          "author_url": "",
          "post_date": "01/19/2026 17:37:45",
          "content": "<p>You should watch out for the leakage.</p>",
          "votes": null,
          "replies": []
        }
      ]
    }
  ],
  "raw_markdown_by_id": {
    "3393490": "In competitions with small datasets (like this one with ~350 unique training images), the Public LB is calculated on maybe 20-30% of the test data. That means the leaderboard score is based on just ~50-100 images.\nIf you tune your model to improve the LB score on those 50 images, you are overfitting the leaderboard.\nWhen the Private LB (the other 70%) is revealed at the end, models that chased the Public LB usually crash. Models with robust CV rise to the top.\n\nThus, I think we need to focus on improving CV",
    "3393492": "![](https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F8a809d9e8c4d657c631db295afda0c25%2FScreenshot%202026-01-19%20at%2013.11.14.png?generation=1768803103667605&alt=media)\n![](https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F2832287%2F5e22a1b48e1d7d4b40352110ff1e24c0%2FScreenshot%202026-01-19%20at%2013.12.21.png?generation=1768803174037558&alt=media)",
    "3393731": "I think that LB is more important. CV seems to be a bit leaky.",
    "3393747": "Yeah, you are right, I neglected the info. But I think both 357 and 800 images are few to build better model that generalizes well.",
    "3393748": "You should watch out for the leakage."
  },
  "source": "meta"
}