FAQs for Subjective Ratings (MOHs)
by Mathandski, Apr 3, 2025, 9:24 PM
If you haven't already, here's the original MOHs handout by Evan Chen prior to this blog post for context.
Over the past few months, you may have come across my posts on HSO such as this one where I posted a subjective rating (MOHs)
Why did you make the ratings?
I find it logical to begin with why I made these ratings in the first place. Whenever someone asks me about a certain problem, I try to formulate my response based on the extent to which I am able to help them with the question. Having these ratings available efficiently facilitates this process. A lower rating means I'd be able to explain everything clearly/quickly so I can jump right in; a higher rating means I would need to spend extra time reviewing my own solution before being able to help. Therefore, I emphasize that the intended function of my ratings is primarily for my own personal use. I posted these publicly to AoPS so that they are publicly accessible to those who are interested. This is distinctively different from Evan's ratings, whose primary purpose is a guide for students.
Your ratings are too high/low
I did try to base my ratings off of Evan Chen's scale such that they can more or less double as a guide. However, while I look at the MOHs ratings of all the problems to build intuition, I only rate problems I solved. Therefore, it is inevitable that my ratings are deflated. Overall, comparing my published ratings with Evan's ratings, mine are consistently Evan -4.5M. Conversely, I tried rating problems I could not solve today and my rating is on average Evan +6.7M. This reflects the subjective nature of MOHs ratings - please take them with a grain of salt!
While I will strive for objectivity, perceived hardness is inevitably subjective by nature.
How can people use difficulty ratings?
I personally found Evan Chen's MOHs ratings extremely helpful in:
1. Evaluating my own level to be wiser with the goals I set for the year
2. Selecting an appropriately difficult problem during practice
3. Discover the subject weaknesses we may have
I hope that my ratings could provide the same assistance.
Over the past few months, you may have come across my posts on HSO such as this one where I posted a subjective rating (MOHs)
1434
of the problem. Consider this blog post as a FAQ for these ratings,Why did you make the ratings?
I find it logical to begin with why I made these ratings in the first place. Whenever someone asks me about a certain problem, I try to formulate my response based on the extent to which I am able to help them with the question. Having these ratings available efficiently facilitates this process. A lower rating means I'd be able to explain everything clearly/quickly so I can jump right in; a higher rating means I would need to spend extra time reviewing my own solution before being able to help. Therefore, I emphasize that the intended function of my ratings is primarily for my own personal use. I posted these publicly to AoPS so that they are publicly accessible to those who are interested. This is distinctively different from Evan's ratings, whose primary purpose is a guide for students.
Your ratings are too high/low
I did try to base my ratings off of Evan Chen's scale such that they can more or less double as a guide. However, while I look at the MOHs ratings of all the problems to build intuition, I only rate problems I solved. Therefore, it is inevitable that my ratings are deflated. Overall, comparing my published ratings with Evan's ratings, mine are consistently Evan -4.5M. Conversely, I tried rating problems I could not solve today and my rating is on average Evan +6.7M. This reflects the subjective nature of MOHs ratings - please take them with a grain of salt!
While I will strive for objectivity, perceived hardness is inevitably subjective by nature.
How can people use difficulty ratings?
I personally found Evan Chen's MOHs ratings extremely helpful in:
1. Evaluating my own level to be wiser with the goals I set for the year
2. Selecting an appropriately difficult problem during practice
3. Discover the subject weaknesses we may have
I hope that my ratings could provide the same assistance.
April 2025
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