Sudoku Online : Grading Sudokus


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Some Stats on Solving Times in the Daily Competitions read »

We have compiled some charts on solving times for Sudokus and Jigsaw Sudokus taken over a 60 day period. Many people have expressed an interest in comparing themselves with the community average and we also promised to provide some further information having obliged solvers to pick their time when submitting a solution. We thank you for that and the data is helping us fine tune the grading, but its interesting in its own right. I'm sure there are a few comments people would like to make and this thread is open for your feedback:

Forum Thread.

How Long Did You Take to Finish a Puzzle?

We are always interested to hear from our visitors and one of the common themes is the difficulty level of the Sudoku and the Jigsaw Sudoku. Sometimes we hear that hard ones can be easier than the moderates or the easy ones are hard. Of course, nobody ever writes to say when the grading is just right!.

We would like to invite you to tell us how long it takes you to complete our Daily Sudoku and Jigsaw Sudoku. We can then look at the average times and compare them with our own scoring to see how often (or not) we hit the mark.

We use a statistical method based on the results from many thousands of sudoku puzzles to decide how difficult they are. We get a score back based on two factors:

The rate at which squares can be solved - an easy one will have many more independent solutions, while a difficult puzzle should require a specific sequence of solving.

The type of solving strategies required. There are very easy strategies which we all use. However, to complete a difficult sudoku you will have to employ something special. We factor in the strategies, weighting them according to difficulty.

One interesting fact: the number of clues does not seem to have much bearing on the grade level. We publish between 22 and 28 clue puzzles normally. Jigsaws range from 19 to 28.

All our sudoku and jigsaw sudoku are guaranteed to be solved logically (unless we publish a special list of 'unsolvables') and they are guaranteed to have a single solution.

With your help we are sure we will be able to compile a useful measure to compare with our grading.

The Archive in the Daily Competition now states the average time to complete those Sudokus. Many thanks for taking part

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