<prompt> Human: About a month ago, I applied for a credit card. I was approved, and received a letter saying that my credit score was 709. After hearing about CreditKarma, I went there and found my score was 727. Is it normal for scores to change that much in such a short time, or is CreditKarma just not very accurate?Another thing that confuses me is the credit simulator. Everything I do seems to lower my credit score. Adding 24-months of on time payments will lower it to 707. Paying off credit card balances will lower it to 713. Am I doing something wrong, or is the site just buggy?  <response>: CreditKarma is extremely accurate in that the score they give you is almost real time. It is inaccurate in that the score they are giving you isnt a FICO, its a proprietary score calculated by Transunion, one of the 3 major credit bureaus. One of the nuances of credit is that often the 3 reports will be different, sometimes for good reason. And obvious example of this is a credit card company that only does a single inquiry with a single bureau. In this case, that bureaus report will be different than the other 2.I have no knowledge of transunions score that they provide, but its possible that things that seem good to you are potentially bad in the model. Credit scores are a tricky game, made even trickier by the fact everybody has their own these days. 