What is an Error Log?
One of the most important parts of test prep is learning from your mistakes. To do that, of course, you need to remember your mistakes. An error log is a great way to record, review, and remember missed answers. This kind of log is also sometimes called a mistake journal. In an error log/mistake journal, you make note of specific questions you've missed. You also record details about question format and content, and details about why you missed each question. For general tips on error logging, read this Magoosh article.
How to Format Your Error Log
Now, a lot of test preppers log their missed questions in a spreadsheet, with columns for section, question type, academic concepts in the questions, and so on. But Magoosh actually recommends a more in-depth approach.
In other words, we recommend a log that's more "journal-format." When you make note of your mistakes, don't just indicate what the question was and what your answer was. To truly learn from your mistakes, you should go a few steps further in your error log. For any missed question, think about what actually went wrong, and make note of your exact mistake. What was the flaw in your thinking or approach? And what can you differently when you encounter similar questions in the future? Also really take time to think about and note the exact concepts and strategies involved in your missed questions.
As you journal your mistakes in detail, you should see a pattern of errors emerge. A well-designed error log creates a profile of the kinds of mistakes you most frequently make. Such a mistake journal also allows you to map your path to success. By making note of the reasons you miss answers and the things you could do differently next time, you identify your weaknesses and find the best ways to address them.
Be sure to also record the source of each question, whether it's a web link, a screenshot, or a page number in one of your test prep books. As you review your error log, it's good to have fast, direct access to the question in full.
Mistake Journal Templates: Two Sample Error Logs
There are two different, common, and useful formats for error logging. There is the "long format" error log, which looks at individual questions in great detail. Then there's the "short format" error log. The shorter format gives you a briefer overview of each missed question, while still covering all the most important info. Which one is best for you? That depends a lot on your own learning needs and preferences. Some students even switch between the two formats, depending on what they're studying and what kind of progress they've been making.
Below is a template for each format. While these templates deal with GRE and GMAT questions, they really do work for just about any standardized test.
Special thanks to Matthew Slayton (Magoosh Subject Matter Expert) and Andrew Furney (Magoosh student) for filling the templates with great actual notes!