Usually you don't need the correction factor and you should leave it at 100%. In case you don't convey your real conversion values to AdWords but falsified values at a steady factor, you can use the correction factor to make the real values accessible for Adspert.
Your real conversion value is 10,- EUR. To leave Google in the dark about how much a conversion is worth to you, you convey a conversion value of 50,- EUR to AdWords. In order that Adspert doesn't optimize based on wrong values, you set a correction factor of 20%. This way Adspert will work with a value of 50,- EUR * 20% = 10,- EUR.
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