Comparing This Year Against Last Year

Why month against month misleads

Most local service businesses have a strong seasonal pattern, and month-on-month change is dominated by it.

Enquiries down twenty percent from October to November is not a finding, it is November. The same drop happened last year and the year before, and reacting to it as though something broke leads to cancelling things that were working.

The reverse error is equally common. A rise into your busy season gets attributed to whatever changed recently, and a redesign gets credit for the weather.

What the annual comparison removes

By comparing November against the previous November, the seasonal component is held roughly constant. What remains is closer to the effect of everything you have done.

It also aligns the calendar features that repeat: the same holidays, the same school terms, and the same weather pattern approximately.

That is not perfect, since seasons vary and calendars shift, and it is considerably better than any comparison against an adjacent month.

What to compare

The first is the one that matters and the others explain it.

The comparison that is not valid

Several things break an annual comparison, and knowing them prevents wrong conclusions.

A change in how conversions are counted, which makes this year's figure incomparable with last year's regardless of what happened.

A platform change, including a new analytics version or a redefined metric. Comparing across one is comparing two different measurements.

A site migration, which frequently interrupts tracking for a period.

Something exceptional in the base year, such as an unusually severe season, a competitor closing, or a one-off large contract.

That last one is worth noting deliberately, because a business comparing against an exceptional year concludes it is declining when it is returning to normal.

The two-year view

Better than one where the data exists.

Three points describe a trend; two describe a difference. A figure up on last year and down on the year before means something different from one rising steadily.

It also dilutes the exceptional-year problem, since an unusual base year is visible as an outlier rather than being mistaken for the norm.

For a business with three years of records, plotting the same month across all three takes minutes and answers more than any single comparison.

Aligning the periods properly

A practical detail that changes the numbers more than expected.

Months contain different numbers of working days and weekends year to year, and a comparison of two Novembers may be comparing twenty working days against twenty-two.

Where the difference matters, comparing on a per-working-day basis or comparing quarters instead removes it. For most small businesses the effect is small enough to note rather than correct, and it is worth knowing before reading too much into a modest change.

Holidays moving between months, which happens with Easter, is the version of this that catches people out.

What to do with the finding

The point of the exercise, since a number without a decision attached is administration.

Enquiries up with sessions flat means the site converts better, and whatever changed is worth extending. Sessions up with enquiries flat means visibility improved and conversion did not, which is a site problem rather than a marketing one. Both down means something needs investigating rather than accepting.

Each of those points somewhere specific, which is more than a monthly report typically produces.

Making it possible

The requirement is having recorded last year's figures in a form that still exists.

Platforms retain data for limited periods and change how it is presented, which means a screenshot or an export taken at the time is worth more than a dashboard you intend to consult later.

Twenty minutes each December, recording the year's figures with their definitions, makes every subsequent comparison possible. That is the same discipline as recording a baseline before a change, applied on an annual cycle instead, as covered in setting a baseline before you change anything.

Frequently asked questions

West Coast Media Solutions Inc. provides web design, web development, hosting, digital marketing, and business consulting to organisations across Canada, drawing on more than twenty-five years in the field.