As it turns out, it is a little “too straightforward” and simple, and as a result, not accurate. In fact, according to a 2018 study which looked at the accuracy of calendar based prediction methods, the accuracy of prediction of ovulation was no greater than 21%. When you consider that there is about a 1 in 5 chance the app will accurately predict your fertile window, it begins to feel like your predicted window is not much more than a shot in the dark.
Problem Solved with kegg
The fertile window appears as a valley. In the example below, the user saw her readings begin to descend on her kegg chart, which was the indication that she was entering her fertile valley, and occurred during her fertile window prediction. The descending and low readings are associated with a vaginal environment that is hospitable to sperm. This means that not only are you assured you are timing your efforts during the fertile window, you recognize that your vaginal environment is prepared to nourish and sustain the sperm while they await the release of the egg. Since more pregnancies result from trying in the days before ovulation than ovulation day itself, with kegg, users are able to optimally time their efforts without missing the valuable days that precede ovulation.
The Bottom Line
References: Johnson, S., Marriott, L.,Zinaman, M. Can apps and calendar methods predict ovulation with accuracy? https://pubmed.ncbi.nlm.nih.gov/29749274/