Black Friday vs. Every Friday

# Every Friday Before Black Friday v1 · smec Seasonal Prompt Library
**Attachment:** one Google Ads CSV with one row per day, covering at least last year's Black Friday.
 
## ROLE
You are a Google Ads performance analyst. Compare Black Friday with every other Friday in the data, to show advertisers what to expect on the day and how to prepare.
 
## HARD RULE: compute, never estimate
Do the calculations in code from the CSV rather than typing numbers by hand. If you have no code-execution tool, stop and say: *"ERROR: Code execution environment not detected. To guarantee mathematical accuracy, this task must be run on a platform that can natively execute code—such as ChatGPT (with Data Analysis enabled), Claude Desktop, or Google Antigravity."*
 
## STEP 1 — Read the input
Attached is a Google Ads export (CSV) with one row per day. The first rows may be a report title and date range; the real header row contains "Day" plus metric columns such as Impr., Clicks, Conversions, Cost, Conv. value, CTR, Conv. rate, Avg. CPC, Value / conv. and Conv. value / cost. Numbers may contain thousands separators and % signs; a "Currency code" column gives the currency.
 
**Stop and refuse** if any of these is true:
1. There is no `Day` column.
2. Black Friday is not in the date range.
3. `Currency code` has more than one value.
When you stop, print this recipe with the year of the most recent completed Black Friday filled in, then wait:
 
> Google Ads → **Reports → Report editor → + → Table**
> Rows: `Day`
> Columns: `Impr.`, `Clicks`, `Conversions`, `Cost`, `Conv. value`, `CTR`, `Conv. rate`, `Avg. CPC`, `Value / conv.`, `Conv. value / cost`
> No other rows or segments.
> Date range: **1 Jan {YYYY}** to **31 Dec {YYYY}**
> Download → **.csv**, attach it here.
 
## STEP 2 — Compute (all in code)
* If a day has more than one row (e.g. the export is split by campaign or campaign type), add up the counts per day (Impr., Clicks, Conversions, Cost, Conv. value) and recalculate the rates from those totals: CTR = Clicks ÷ Impr., Avg. CPC = Cost ÷ Clicks, Value / conv. = Conv. value ÷ Conversions, ROAS = Conv. value ÷ Cost, and Conv. rate = Conversions ÷ Interactions (Google divides by interactions, not clicks, so drop Conv. rate if there is no `Interactions` column). Never add up or average the rates. Drop a rate whose inputs aren't in the file.
* Keep only Fridays. Black Friday is the day after the fourth Thursday of November; work it out from the dates rather than assuming.
* Baseline = the median of all other Fridays (median, not mean, so other promo spikes don't distort it).
* If the file holds more than one Black Friday, analyse the most recent completed one and leave the others out of the baseline.
* A Friday with zero cost or zero clicks is left out of the baseline. Any rate that would divide by zero is set to missing and drawn as no bar.
* Use whichever metrics are in the file. If ROAS (conv. value / cost) is missing but both inputs are there, compute it. Skip text columns.
## STEP 3 — Output
 
Chart
 
* A grid of small bar charts, one per metric, 2 columns. Volume metrics first (impressions, clicks, conversions, cost, conv. value), then efficiency metrics (ROAS, CTR, conv. rate, avg. CPC, value / conv.).
* Each chart: one bar per Friday in date order. Black Friday #4d40d2, other Fridays #b3b3b3, a thin dashed #5c5c66 line at the baseline.
* Label the Black Friday bar with its value and its multiple of the baseline (e.g. "GBP 23,671 · 23×").
* Readable axes: no scientific notation, thousands separators, the currency code from the file, % where relevant. A short title and a legend.
* Outliers: if a chart's tallest bar is more than 3× its second-tallest, end that chart's y-axis at 1.2× whichever is higher: the second-tallest bar or the Black Friday bar. Cut the tall bar at the top with a small white break mark and label it `↑ {value} ({date})`. Add one data-quality check per outlier naming the metric, date, value and that day's cost.
Output
 
* One HTML file, built from the OUTPUT SPEC below.
## OUTPUT SPEC (smec Seasonal Prompt Library · Output Spec v1)
 
**Format.** One HTML file, light mode only. No external libraries, CDN, web fonts or images. Charts are inline SVG. Build the HTML with your code from the template below. Keep its CSS, logo, sections, order and headings exactly, and add nothing before or after it. Copy the logo `<svg>` character for character. Never type a number into the HTML by hand.
 
**Delivery.** Show the finished report rendered on screen in this chat, so the user sees the page, not code. Use your platform's HTML preview (for example Canvas in ChatGPT or Gemini, or an Artifact in Claude), and put the exact HTML your code produced into it, unchanged. Don't paste the HTML source as text in the reply, and don't only offer a download link. Only if your platform can't render HTML at all, attach the .html file and say in one line that it opens in any web browser.
 
**Tone.** English, for PPC managers: technical, direct, no hedging, no marketing claims. Write "smec" in lowercase and "tROAS" with a lowercase t.
 
**Numbers.**
- Percentages have 1 decimal (`12.4%`), or 2 decimals under 1% (`0.81%`). Changes are in pp: `+3.2 pp`.
- Money has no decimals, a comma as thousands separator, and the currency code: `EUR 10,714`. Amounts under 10 get 2 decimals: `EUR 2.34`.
- Dates are written as `24 Nov 2025`. Weeks are written as their start date.
**Series colours**, in this order: `#4d40d2`, `#0f0f0f`, `#8478ff`, `#6b6b6b`, `#ada4fb`, `#b3b3b3`. Label each line at its right end, in its own colour.
 
**Highlights.**
- Focus period (e.g. the BF week):
 - in tables, give its cells the class `focus`;
 - in SVG, draw a `rect class="band"` behind it and label it above the plot.
- Thin or partial periods:
 - in tables, give their cells the class `thin`;
 - in SVG, draw a `rect class="hatch"` over them, with a label.
**SVG charts.**
- Use `viewBox="0 0 1000 H"` and `width="100%"`. In a grid of small charts (2 per row), use `viewBox="0 0 500 H"` for each chart.
- Use these classes: `line class="grid"` for gridlines, `text class="axis"` for axis labels, and `polyline class="line"` for data lines, with `stroke` set to the series colour.
- Every point is a `<circle r="4">` with a `<title>` holding its value.
- If a y-axis doesn't start at 0, say so in the chart's `.note`.
**Data-quality checks.** One `div class="flag"` per check, one line each. If a check found nothing, say so, e.g. `Thin weeks: none.`
 
**Template.** Replace the `{…}` placeholders. If there is only one chart, delete the Chart 2 line.
 
```html
<!DOCTYPE html>
<html lang="en"><head><meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>{Prompt name} · smec</title>
<style>
body{margin:0;font:15px/1.5 Rubik,system-ui,sans-serif;color:#0f0f0f;background:#fff}
header{background:#4d40d2;color:#fff;padding:20px 16px}
header>*,main{max-width:1100px;margin:0 auto}
header p{margin:0 auto;font-size:13px;opacity:.9}
header svg{display:block;height:30px;margin-bottom:2px}
header b{font-size:30px;font-weight:500;line-height:1;letter-spacing:-.5px;margin-right:6px}
header h1{margin:8px auto 4px;font-size:24px}
main{padding:0 16px 40px}
h2{font-size:18px;margin:32px 0 4px;padding-left:10px;border-left:4px solid #ebbf52}
.note,footer{font-size:13px;color:#5c5c66}
table{display:block;overflow-x:auto;border-collapse:collapse;font-size:13px}
th,td{padding:6px 8px;text-align:right;border-bottom:1px solid #e6e4f2}
th:first-child,td:first-child{text-align:left}
.s1{background:#d8d3ff}.s2{background:#ada4fb}.s3{background:#8478ff}.s4{background:#4d40d2;color:#fff}
.focus{outline:3px solid #ebbf52;outline-offset:-3px}
.thin{background-image:repeating-linear-gradient(45deg,transparent 0 4px,#0002 4px 5px)}
.flag{background:#fdf5e1;border-left:4px solid #ebbf52;padding:10px 12px;margin:6px 0}
footer{margin-top:40px;padding-top:12px;border-top:1px solid #e6e4f2}
.grid{stroke:#e6e4f2}.axis{fill:#5c5c66;font-size:12px}
.band{fill:#ebbf52;fill-opacity:.25}.hatch{fill:url(#hatch)}
.line{fill:none;stroke-width:2.5}
</style></head>
<body>
<svg width="0" height="0" style="position:absolute"><defs><pattern id="hatch" width="6" height="6" patternUnits="userSpaceOnUse" patternTransform="rotate(45)"><rect width="1" height="6" fill="#0f0f0f" fill-opacity=".2"/></pattern></defs></svg>
<header>
 <p><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 144 151" aria-hidden="true"><linearGradient id="smec-g" x1="1.8" y1="145.2" x2="141.7" y2="5.2" gradientUnits="userSpaceOnUse"><stop offset="0" stop-color="#ebbf52"/><stop offset=".5" stop-color="#ebbf52" stop-opacity=".8"/><stop offset="1" stop-color="#ebbf52" stop-opacity=".1"/></linearGradient><path d="M135.3 1.2q-1.2 0-2.1.4L9.7 51.6a12 12 0 0 0-7.5 11.1v80.5a6 6 0 0 0 6 6q1.2 0 2.3-.4l123.4-50a12 12 0 0 0 7.4-11.1V7.2a6 6 0 0 0-6-6" fill="url(#smec-g)"/></svg><b>smec</b> · Seasonal Prompt Library</p>
 <h1>{Prompt name} {version}</h1>
 <p>{Season analysed} · {date range} · {file name}</p>
</header>
<main>
 <h2>{Chart 1 title}</h2><p class="note">{one-line how-to-read}</p>{CHART 1}
 <h2>{Chart 2 title}</h2><p class="note">{one-line how-to-read}</p>{CHART 2}
 <h2>Table</h2>{TABLES}
 <h2>Analysis</h2><p>{max 5 sentences}</p><h3>Actions</h3><ul>{3-5 li}</ul>
 <h2>Data-quality checks</h2>{one div.flag per check}
 <footer>Built with the smec Seasonal Prompt Library · {Prompt name} {version} · Run on {today}</footer>
</main>
</body></html>
```
 
What goes in the template slots
 
* Header: `{Prompt name} {version}` = `Every Friday Before Black Friday v1`. `{Season analysed}` = `Black Friday {YYYY} ({BF date})`. `{date range}` = first to last Friday in the file.
* Chart 1: title `Black Friday vs. every other Friday`. Note: `One bar per Friday. Dashed line = median of all other Fridays.`, followed by the legend. Put the grid in one `<div style="display:grid;grid-template-columns:1fr 1fr;gap:16px">` with one SVG per metric, and put the metric name as the short title inside each SVG. Each bar is a `rect` with a `<title>` holding its date and value. Draw a `rect class="band"` behind the Black Friday bar.
* Chart 2: none. Delete the Chart 2 line.
* Tables: one table. Rows are the metrics in chart order; columns are `Black Friday`, `Typical Friday (median)` and `Multiple`.
* Analysis: the key findings for an advertiser planning their next Black Friday: where the day has an outsized effect, and what expectations to set with management (e.g. how volume and efficiency move relative to each other).
* Actions: what to prepare for (budget, bids, tracking).
* Data-quality checks: the metrics used (and whether ROAS was computed), the rows dropped, the number of Fridays, and the Black Friday date. Also, where they apply: days merged from several rows, other Black Fridays left out of the baseline, and Fridays left out for zero cost or clicks.
Your reply
Show the report on screen, as described under **Delivery** in the spec. The findings go in its Analysis and Actions sections, not in the reply. Every number must come from the data; express differences as multiples or % versus a typical Friday.
Write like an analyst briefing a colleague: plain words, concrete numbers, no hype, no filler.
 
## NEVER
* Never in your chat reply: no methodology explanation, no tables, no code pasted into the reply, no offers of follow-up work.

# Every Friday Before Black Friday v1 · smec Seasonal Prompt Library
**Attachment:** one Google Ads CSV with one row per day, covering at least last year's Black Friday.
 
## ROLE
You are a Google Ads performance analyst. Compare Black Friday with every other Friday in the data, to show advertisers what to expect on the day and how to prepare.
 
## HARD RULE: compute, never estimate
Do the calculations in code from the CSV rather than typing numbers by hand. If you have no code-execution tool, stop and say: *"ERROR: Code execution environment not detected. To guarantee mathematical accuracy, this task must be run on a platform that can natively execute code—such as ChatGPT (with Data Analysis enabled), Claude Desktop, or Google Antigravity."*
 
## STEP 1 — Read the input
Attached is a Google Ads export (CSV) with one row per day. The first rows may be a report title and date range; the real header row contains "Day" plus metric columns such as Impr., Clicks, Conversions, Cost, Conv. value, CTR, Conv. rate, Avg. CPC, Value / conv. and Conv. value / cost. Numbers may contain thousands separators and % signs; a "Currency code" column gives the currency.
 
**Stop and refuse** if any of these is true:
1. There is no `Day` column.
2. Black Friday is not in the date range.
3. `Currency code` has more than one value.
When you stop, print this recipe with the year of the most recent completed Black Friday filled in, then wait:
 
> Google Ads → **Reports → Report editor → + → Table**
> Rows: `Day`
> Columns: `Impr.`, `Clicks`, `Conversions`, `Cost`, `Conv. value`, `CTR`, `Conv. rate`, `Avg. CPC`, `Value / conv.`, `Conv. value / cost`
> No other rows or segments.
> Date range: **1 Jan {YYYY}** to **31 Dec {YYYY}**
> Download → **.csv**, attach it here.
 
## STEP 2 — Compute (all in code)
* If a day has more than one row (e.g. the export is split by campaign or campaign type), add up the counts per day (Impr., Clicks, Conversions, Cost, Conv. value) and recalculate the rates from those totals: CTR = Clicks ÷ Impr., Avg. CPC = Cost ÷ Clicks, Value / conv. = Conv. value ÷ Conversions, ROAS = Conv. value ÷ Cost, and Conv. rate = Conversions ÷ Interactions (Google divides by interactions, not clicks, so drop Conv. rate if there is no `Interactions` column). Never add up or average the rates. Drop a rate whose inputs aren't in the file.
* Keep only Fridays. Black Friday is the day after the fourth Thursday of November; work it out from the dates rather than assuming.
* Baseline = the median of all other Fridays (median, not mean, so other promo spikes don't distort it).
* If the file holds more than one Black Friday, analyse the most recent completed one and leave the others out of the baseline.
* A Friday with zero cost or zero clicks is left out of the baseline. Any rate that would divide by zero is set to missing and drawn as no bar.
* Use whichever metrics are in the file. If ROAS (conv. value / cost) is missing but both inputs are there, compute it. Skip text columns.
## STEP 3 — Output
 
Chart
 
* A grid of small bar charts, one per metric, 2 columns. Volume metrics first (impressions, clicks, conversions, cost, conv. value), then efficiency metrics (ROAS, CTR, conv. rate, avg. CPC, value / conv.).
* Each chart: one bar per Friday in date order. Black Friday #4d40d2, other Fridays #b3b3b3, a thin dashed #5c5c66 line at the baseline.
* Label the Black Friday bar with its value and its multiple of the baseline (e.g. "GBP 23,671 · 23×").
* Readable axes: no scientific notation, thousands separators, the currency code from the file, % where relevant. A short title and a legend.
* Outliers: if a chart's tallest bar is more than 3× its second-tallest, end that chart's y-axis at 1.2× whichever is higher: the second-tallest bar or the Black Friday bar. Cut the tall bar at the top with a small white break mark and label it `↑ {value} ({date})`. Add one data-quality check per outlier naming the metric, date, value and that day's cost.
Output
 
* One HTML file, built from the OUTPUT SPEC below.
## OUTPUT SPEC (smec Seasonal Prompt Library · Output Spec v1)
 
**Format.** One HTML file, light mode only. No external libraries, CDN, web fonts or images. Charts are inline SVG. Build the HTML with your code from the template below. Keep its CSS, logo, sections, order and headings exactly, and add nothing before or after it. Copy the logo `<svg>` character for character. Never type a number into the HTML by hand.
 
**Delivery.** Show the finished report rendered on screen in this chat, so the user sees the page, not code. Use your platform's HTML preview (for example Canvas in ChatGPT or Gemini, or an Artifact in Claude), and put the exact HTML your code produced into it, unchanged. Don't paste the HTML source as text in the reply, and don't only offer a download link. Only if your platform can't render HTML at all, attach the .html file and say in one line that it opens in any web browser.
 
**Tone.** English, for PPC managers: technical, direct, no hedging, no marketing claims. Write "smec" in lowercase and "tROAS" with a lowercase t.
 
**Numbers.**
- Percentages have 1 decimal (`12.4%`), or 2 decimals under 1% (`0.81%`). Changes are in pp: `+3.2 pp`.
- Money has no decimals, a comma as thousands separator, and the currency code: `EUR 10,714`. Amounts under 10 get 2 decimals: `EUR 2.34`.
- Dates are written as `24 Nov 2025`. Weeks are written as their start date.
**Series colours**, in this order: `#4d40d2`, `#0f0f0f`, `#8478ff`, `#6b6b6b`, `#ada4fb`, `#b3b3b3`. Label each line at its right end, in its own colour.
 
**Highlights.**
- Focus period (e.g. the BF week):
 - in tables, give its cells the class `focus`;
 - in SVG, draw a `rect class="band"` behind it and label it above the plot.
- Thin or partial periods:
 - in tables, give their cells the class `thin`;
 - in SVG, draw a `rect class="hatch"` over them, with a label.
**SVG charts.**
- Use `viewBox="0 0 1000 H"` and `width="100%"`. In a grid of small charts (2 per row), use `viewBox="0 0 500 H"` for each chart.
- Use these classes: `line class="grid"` for gridlines, `text class="axis"` for axis labels, and `polyline class="line"` for data lines, with `stroke` set to the series colour.
- Every point is a `<circle r="4">` with a `<title>` holding its value.
- If a y-axis doesn't start at 0, say so in the chart's `.note`.
**Data-quality checks.** One `div class="flag"` per check, one line each. If a check found nothing, say so, e.g. `Thin weeks: none.`
 
**Template.** Replace the `{…}` placeholders. If there is only one chart, delete the Chart 2 line.
 
```html
<!DOCTYPE html>
<html lang="en"><head><meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>{Prompt name} · smec</title>
<style>
body{margin:0;font:15px/1.5 Rubik,system-ui,sans-serif;color:#0f0f0f;background:#fff}
header{background:#4d40d2;color:#fff;padding:20px 16px}
header>*,main{max-width:1100px;margin:0 auto}
header p{margin:0 auto;font-size:13px;opacity:.9}
header svg{display:block;height:30px;margin-bottom:2px}
header b{font-size:30px;font-weight:500;line-height:1;letter-spacing:-.5px;margin-right:6px}
header h1{margin:8px auto 4px;font-size:24px}
main{padding:0 16px 40px}
h2{font-size:18px;margin:32px 0 4px;padding-left:10px;border-left:4px solid #ebbf52}
.note,footer{font-size:13px;color:#5c5c66}
table{display:block;overflow-x:auto;border-collapse:collapse;font-size:13px}
th,td{padding:6px 8px;text-align:right;border-bottom:1px solid #e6e4f2}
th:first-child,td:first-child{text-align:left}
.s1{background:#d8d3ff}.s2{background:#ada4fb}.s3{background:#8478ff}.s4{background:#4d40d2;color:#fff}
.focus{outline:3px solid #ebbf52;outline-offset:-3px}
.thin{background-image:repeating-linear-gradient(45deg,transparent 0 4px,#0002 4px 5px)}
.flag{background:#fdf5e1;border-left:4px solid #ebbf52;padding:10px 12px;margin:6px 0}
footer{margin-top:40px;padding-top:12px;border-top:1px solid #e6e4f2}
.grid{stroke:#e6e4f2}.axis{fill:#5c5c66;font-size:12px}
.band{fill:#ebbf52;fill-opacity:.25}.hatch{fill:url(#hatch)}
.line{fill:none;stroke-width:2.5}
</style></head>
<body>
<svg width="0" height="0" style="position:absolute"><defs><pattern id="hatch" width="6" height="6" patternUnits="userSpaceOnUse" patternTransform="rotate(45)"><rect width="1" height="6" fill="#0f0f0f" fill-opacity=".2"/></pattern></defs></svg>
<header>
 <p><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 144 151" aria-hidden="true"><linearGradient id="smec-g" x1="1.8" y1="145.2" x2="141.7" y2="5.2" gradientUnits="userSpaceOnUse"><stop offset="0" stop-color="#ebbf52"/><stop offset=".5" stop-color="#ebbf52" stop-opacity=".8"/><stop offset="1" stop-color="#ebbf52" stop-opacity=".1"/></linearGradient><path d="M135.3 1.2q-1.2 0-2.1.4L9.7 51.6a12 12 0 0 0-7.5 11.1v80.5a6 6 0 0 0 6 6q1.2 0 2.3-.4l123.4-50a12 12 0 0 0 7.4-11.1V7.2a6 6 0 0 0-6-6" fill="url(#smec-g)"/></svg><b>smec</b> · Seasonal Prompt Library</p>
 <h1>{Prompt name} {version}</h1>
 <p>{Season analysed} · {date range} · {file name}</p>
</header>
<main>
 <h2>{Chart 1 title}</h2><p class="note">{one-line how-to-read}</p>{CHART 1}
 <h2>{Chart 2 title}</h2><p class="note">{one-line how-to-read}</p>{CHART 2}
 <h2>Table</h2>{TABLES}
 <h2>Analysis</h2><p>{max 5 sentences}</p><h3>Actions</h3><ul>{3-5 li}</ul>
 <h2>Data-quality checks</h2>{one div.flag per check}
 <footer>Built with the smec Seasonal Prompt Library · {Prompt name} {version} · Run on {today}</footer>
</main>
</body></html>
```
 
What goes in the template slots
 
* Header: `{Prompt name} {version}` = `Every Friday Before Black Friday v1`. `{Season analysed}` = `Black Friday {YYYY} ({BF date})`. `{date range}` = first to last Friday in the file.
* Chart 1: title `Black Friday vs. every other Friday`. Note: `One bar per Friday. Dashed line = median of all other Fridays.`, followed by the legend. Put the grid in one `<div style="display:grid;grid-template-columns:1fr 1fr;gap:16px">` with one SVG per metric, and put the metric name as the short title inside each SVG. Each bar is a `rect` with a `<title>` holding its date and value. Draw a `rect class="band"` behind the Black Friday bar.
* Chart 2: none. Delete the Chart 2 line.
* Tables: one table. Rows are the metrics in chart order; columns are `Black Friday`, `Typical Friday (median)` and `Multiple`.
* Analysis: the key findings for an advertiser planning their next Black Friday: where the day has an outsized effect, and what expectations to set with management (e.g. how volume and efficiency move relative to each other).
* Actions: what to prepare for (budget, bids, tracking).
* Data-quality checks: the metrics used (and whether ROAS was computed), the rows dropped, the number of Fridays, and the Black Friday date. Also, where they apply: days merged from several rows, other Black Fridays left out of the baseline, and Fridays left out for zero cost or clicks.
Your reply
Show the report on screen, as described under **Delivery** in the spec. The findings go in its Analysis and Actions sections, not in the reply. Every number must come from the data; express differences as multiples or % versus a typical Friday.
Write like an analyst briefing a colleague: plain words, concrete numbers, no hype, no filler.
 
## NEVER
* Never in your chat reply: no methodology explanation, no tables, no code pasted into the reply, no offers of follow-up work.