Year-over-year(YoY)
Measurement and data
Measurement and data
Year-over-year (YoY) compares a period with exactly the same period one year earlier, for example this month against the same month last year.
The big advantage is that it filters out seasonality. Comparing December with November says little if you have a December peak; December against December does. The same holds for holidays and industry-specific peaks.
Watch the calendar when comparing: match weekdays or the number of working days, because a month with five weekends behaves differently. Google Analytics and Search Console can line this up for you.
YoY works best alongside a short-term comparison. Month-on-month shows what is happening now, YoY whether things are structurally improving.
In practice
Comparing YoY as if last year was normal. An outlier, a campaign or an outage last year makes this year's comparison misleading.
Related terms
- KPIA KPI is a number you steer on because it links directly to a goal, such as qualified enquiries per month or cost per customer.
- ImpressionsAn impression is one view of your ad or search result. Ten impressions can therefore belong to one person.
- ConversionA conversion is an action you defined as valuable: an enquiry, purchase, download or phone call. The conversion rate is the share of visitors who take it.
- Business intelligenceBusiness intelligence (BI) is collecting, combining and visualising company data so you decide on numbers instead of gut feeling.