Why use log2 fold change

In the field of genomics and more generally in bioinformatics , fold changes are defined directly in terms of ratios. Note that this is different to the definition described above. In other words, a change from 30 to 60 is defined as a fold-change of 2. This is also referred to as a "2-fold increase". Similarly, a change from 30 to 15 is referred to as a "2-fold decrease". In genomics, log ratios are often used for analysis and visualization of fold changes.

The log2 log with base 2 is most commonly used. Login before adding your answer. Presumably whoever made the test mistakenly believes the answer to be "A and C".

Note that that's actually wrong. Whoever wrote the test doesn't know enough to have done so. It's one thing to score on a multiple choice quiz and another to know the 'right answer'. Thank you so much again for your help! Thread Tools. All times are GMT The time now is PM. User Name. Remember Me? Mark Forums Read. Similar Threads. Generating heat map from gene list and fold change between different groups.

DESeq2 log2 fold change discrepancy. Learn more. About the log2 fold change Ask Question. Asked 1 year, 2 months ago. Active 5 months ago. Viewed times. It seems that we have two calculations of log fold change. Improve this question. Like RezaRezaei says, the two calculations are the same. I guess there could be differences owing to how computers calculate the values. I don't know how computers do complex math, but I'm guessing that's where the difference lies.

I do think that even for more complex math, precision should be maintained to the third decimal place at least, so how significant would the difference be? Add a comment. Active Oldest Votes. Improve this answer. Sign up or log in Sign up using Google.