Negative Ratings in codechef

I saw many profiles on codechef and found that many participants received negative ratings but can anyone please tell what is the reason for getting negative ratings?

Codechefs rating is based on ELO system which is like relative grading. There is no lower limit so your rating can drop below 0 if your performance is not good.Keep solving questions and it will improve in no time.”- @kcahdog

To get a hang of this, assume initially you have 1000 ratings in the long contests. (It is possible that many people may have around 1000 rating points) Suppose in a contest you were able to solve 4 problems but others with the same rating as yours solved 5 or 6 problems. That means you underperformed as compared to others with same ratings and hence your new rating will decrease. If you solved more problems than expected of you then your rating will increase.

Negative ratings usually occur when you take part in contest and you are unable to submit even a single correct answer.

Not taking part in a contest means your rating will remain same but your rank will decrease/get worse usually because those who had participated will have increased rating and hence increased ranks.