Compare against previous period

Date picker → Compare to → previous period (same days last week / month / year / custom). Metrics show delta. WoW / MoM / YoY analysis.

Written By Salvatore Sinigaglia

Last updated About 1 hour ago

Date picker → Compare to → previous period (same days last week / month / year / custom). Metrics show delta. WoW / MoM / YoY analysis.

Compare against previous period

Status: the period-comparison toggle is currently disabled in Ads Manager — the date picker there is rendered with compareEnabled={false} (verified reports.tsx:1724), so the "Compare to" control is not available on the Ads Manager reports view. The behavior described below applies to surfaces where comparison is enabled (e.g. the date picker component supports it) and to how comparison works conceptually.

Date picker → toggle "Compare to" → pick previous period (same days last week / month / year / custom). When enabled, all metrics show delta (% change) vs the comparison. Useful for WoW + MoM + YoY analysis. Caveat: seasonal effects make "same days last year" more meaningful than "same days last month" for seasonal businesses.

Who is this for

Mediabuyers running weekly / monthly reviews. Anyone comparing this period to a baseline to spot trends.

How to enable comparison

Step 1: Set base date range

In date picker, pick your current period (e.g. "Last 7 days").

Step 2: Toggle Compare to

In date picker, click Compare to toggle.

Step 3: Pick comparison period

Options:

ComparisonWhat it picks
Same days previous periodEqual-length window immediately before base (e.g. Last 7 days = 8-14 days ago)
Same days last weekEqual-length 7 days earlier (for daily/weekly cycles)
Same days last monthEqual days in previous calendar month (e.g. 1-7 of last month vs 1-7 this month)
Same days last yearEqual days 365 days ago (seasonal comparison)
CustomPick specific dates for the comparison

Step 4: Apply

Click Apply. Metrics now show:

  • Current value
  • Comparison value (in smaller text)
  • Delta as % change (color-coded: green positive, red negative)

Example: ROAS 3.2 (+15% vs 2.8 prev)

Common comparison patterns

WoW (Week-over-Week)

  • Base: Last 7 days
  • Compare to: Same days last week (8-14 days ago)
  • Spot week-to-week trends

MoM (Month-over-Month)

  • Base: Last month full
  • Compare to: Previous month
  • Or: Same days this month vs same days last month (for partial-month comparison)

YoY (Year-over-Year)

  • Base: Last month or quarter
  • Compare to: Same period last year
  • Critical for seasonal businesses (e-commerce: Black Friday vs Black Friday last year)

Custom: pre/post event

  • Base: 7 days after product launch
  • Compare to: 7 days before launch
  • Measures launch impact

Where comparison shows

Ads Manager rows

Each metric column shows:

  • Current value
  • Below: delta % (green up, red down)
  • Hover for absolute change

Dashboard KPI strip

Top of dashboard:

  • Each KPI shows current + delta
  • Some show sparkline mini-chart for trend

Reports

CSV + PDF exports include columns for current + previous + delta (if comparison enabled at export time).

Seasonal interpretation

For seasonal businesses (e-commerce, travel, retail):

  • WoW: less meaningful (one off-week distorts)
  • MoM: somewhat meaningful (general trend)
  • YoY: most meaningful (same seasonal context)

Don't expect December's "MoM vs November" to look "normal" — December is its own animal. YoY for accurate read.

Combining with filters

You can apply filters + comparison:

  • Filter to ROAS < 1.5 underperformers
  • Compare to: same days last week
  • See: are the same campaigns underperforming, OR has the bad performance shifted to new ones?

Comparison in reports + exports

When you export with Compare to enabled:

  • CSV: includes columns current_*, previous_*, delta_* per metric
  • PDF: side-by-side or stacked charts for both periods

Useful for stakeholder reports: not just current state, but trend.

What delta colors mean

ColorMeaning
GreenImprovement (depends on metric — see below)
RedDecline
Grey / no color< 1% change (noise)
Bold green / red> 25% significant change

Metric-specific:

  • Higher better: ROAS, conversions, CTR → green for up
  • Lower better: CPA, CPM, frequency → green for down

UI handles this correctly (color reflects "good change", not just numeric direction).

Limits

  • One comparison at a time: can't compare to 2+ periods simultaneously (current vs last week vs last year). Export both separately.
  • Equal-length windows: comparison period auto-matches base length. Custom for unequal (less meaningful).
  • Time aggregation: per-day metrics + per-day comparison work; per-hour comparison less commonly supported.

Late attribution affects comparison

Recent periods (last 24-48h) have less-settled data than older. So comparing "Last 7 days" vs "Same days last week":

  • Last 7 days: Day 1 settled, Day 7 still settling
  • Previous week: fully settled

Delta may look worse than reality for current period. Re-check after 3-7 days for stable comparison.

What you'll see

Date picker with Compare to enabled:

  • Two date chips side-by-side: current + comparison
  • Metric cells show both values
  • Delta in % with color
  • Hover: tooltip with absolute change + comparison details

Common questions

  • "Comparison shows +500% — is that real?": small baseline → big % swings. Check absolute numbers; 1 → 6 = +500% but small impact.
  • "Why does compare to last year look weird?": workspace may not have had data 1 year ago (new account). Comparison requires data in both periods.
  • "Can I compare two custom periods?": yes — pick "Custom" in Compare to → enter dates.
  • "Compare across platforms shows odd deltas": platform mix may have changed (you added a new platform). Filter to consistent platform set.
  • "Comparison metric absent in CSV export": ensure Compare to enabled at export time + Include comparison columns toggle ticked.

Best practices

Use YoY for seasonal

Q4 2026 vs Q4 2025 (not Q4 vs Q3) for ecommerce.

Watch for new factors

If you scaled budget 3x between periods: ROAS likely dropped. Comparison should account for budget scale.

Track delta over time

Don't just look at this week's delta. Track delta-of-delta:

  • Last week ROAS: +15%
  • This week ROAS: +5%
  • Trend: improvement slowing

Reconcile annually

For YoY comparisons: account for changes (new audience added, new platform, etc.). Pure YoY may be apples-to-oranges.

FAQ

How do I compare against a previous period in Wevion?

Note first: the "Compare to" toggle is currently disabled in Ads Manager (compareEnabled={false}), so it's not selectable on that reports view. Where comparison is enabled, you set your base date range in the date picker, toggle Compare to, pick a comparison period, and click Apply. Every metric then shows the current value, the comparison value in smaller text, and the delta as a color-coded percentage change, for example ROAS 3.2 (+15% vs 2.8 prev).

What comparison periods can I pick in Wevion?

Wevion offers Same days previous period (an equal-length window immediately before the base), Same days last week, Same days last month, Same days last year for seasonal comparison, and Custom for specific dates. These support Week-over-Week, Month-over-Month, and Year-over-Year analysis.

What do the delta colors mean in Wevion comparisons?

Green means improvement and red means decline, with grey for changes under 1% (noise) and bold for changes over 25%. Wevion interprets the direction per metric: for higher-is-better metrics like ROAS, conversions, and CTR, up is green, while for lower-is-better metrics like CPA, CPM, and frequency, down is green.

Can I compare more than two periods at once in Wevion?

No. Wevion supports one comparison at a time, so you cannot compare current versus last week versus last year simultaneously. To view multiple baselines, export each comparison separately. Comparison periods also auto-match the base length, so use Custom for unequal windows.

Does the comparison appear in Wevion exports?

Yes, when Compare to is enabled at export time. Wevion CSV exports include current_*, previous_*, and delta_* columns per metric, and PDF exports show side-by-side or stacked charts for both periods. If a comparison column is missing from a CSV, make sure Compare to and the Include comparison columns toggle were on at export.

Steps

  1. In date picker, pick your current period (e.g. "Last 7 days").
  2. In date picker, click Compare to toggle.
  3. Options: | Comparison | What it picks | |---|---| | Same days previous period | Equal-length window immediately before base (e.g. Last 7 days = 8-14 days ago) | | Same days last week | Equal-length 7 days earlier (for daily/weekly cycles) | | Same days last month | Equal days in previous calendar month (e.g. 1-7 of last month vs 1-7 this month) | | Same days last year | Equal days 365 days ago (seasonal comparison) | | Custom | Pick specific dates for the comparison |
  4. Click Apply. Metrics now show: Current value Comparison value (in smaller text) Delta as % change (color-coded: green positive, red negative) Example: ROAS 3.2 (+15% vs 2.8 prev)

Last updated: 2026-05-17