“Peak, high, and low” results correspond to digital OPKs, such as Clear Blue. Digital OPKs can detect different levels of the luteinizing hormone (LH). A "peak" or "positive" result indicates that you will ovulate in the next 24-36 hours and that intercourse in the following 48 hours is the most likely to result in conception. “Positive and negative” results correspond to non-digital OPKs that can only detect if LH is present or not.