Comparing Time Periods in AskBiz
Learn how to use period comparison to spot trends, seasonality, and growth — and avoid the common mistakes that lead to wrong conclusions.
The four comparison modes
AskBiz supports four period comparison modes: Previous period (last week vs the week before, last month vs the month before — good for spotting short-term momentum), Same period last year (this month vs the same month last year — removes seasonality), Rolling 28 days vs previous 28 days (smooths out weekly variation, useful for operational metrics), and Custom (set any start and end date for the comparison). Access these via the comparison dropdown next to the date picker.
When to use year-over-year
Year-over-year (YoY) comparison is the gold standard for most business metrics because it removes the distorting effect of seasonality. If your business sells winter coats, comparing November revenue to October revenue will always look like massive growth — but that tells you nothing about whether the business is improving. Comparing November this year to November last year tells you whether you are growing in a meaningful way. Use YoY for revenue, customer acquisition, and margin comparisons.
When to use previous period
Previous period comparison is most useful for short-cycle operational metrics where you want to see recent momentum: conversion rate this week vs last week, support ticket volume today vs yesterday, stock turnover this month vs last month. It is also useful after a specific change — if you launched a new pricing page on Monday, comparing Monday-Friday this week to last week tells you whether the change worked.
Avoiding base effect mistakes
A base effect distorts percentage comparisons when the comparison period was unusually high or low. If you had a warehouse fire in March last year and no revenue for two weeks, March this year will look like extraordinary growth — but it is just normalisation. AskBiz flags anomalous comparison periods with a warning icon. When you see this, switch to a rolling average or a longer comparison window to get a cleaner read.