> ## Documentation Index
> Fetch the complete documentation index at: https://docs.appliedaifoundation.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Comparative Analysis Tab

> Hour-by-hour lamp efficiency comparison between any two of the 16 UV lamps over a selectable date range.

<Frame caption="Comparative Analysis — lamp-to-lamp efficiency comparison over time">
  <img src="https://mintcdn.com/metaweaveconsultant/Yh8TWLsifrpzxzbC/images/comparative/lamp-comparison.png?fit=max&auto=format&n=Yh8TWLsifrpzxzbC&q=85&s=c860334a26fed2806495bbadb30f18d0" alt="Line chart comparing efficiency of two selected lamps against the fleet average" width="1440" height="900" data-path="images/comparative/lamp-comparison.png" />
</Frame>

## What this tab shows

The Comparative Analysis tab plots two selected UV lamps side-by-side on a single chart, along with the fleet average efficiency across all 16 lamps. This makes it easy to:

* Compare a recently replaced lamp against an aged one to confirm the replacement was effective
* Identify lamps at opposite positions in the diamond array that show asymmetric degradation (possible flow distribution issue)
* Spot whether a lamp's decline is isolated or part of a broader fleet-wide trend

## Default selection

On first load, the tab compares **Lamp 1** vs **Lamp 16** over the previous 30 days. Both lamp selectors and the date range can be changed at any time.

## How data loads

The same two-stage progressive loading pattern used by Trend Analysis applies here:

1. **Stage 1** — Daily aggregated data renders the chart immediately
2. **Stage 2** — Raw 500-record chunks stream in the background, sharpening the chart to hourly resolution

A progress indicator appears bottom-right during streaming. Once streaming is complete, the chart shows up to 300 data points (downsampled if more hourly groups exist).

See [Progressive Data Loading](/methodology/progressive-loading) for full details.

## Lamp selector

Two dropdowns at the top of the tab select Lamp 1 and Lamp 2. Each offers Lamp 01 through Lamp 16. When the selection changes, the chart re-renders from already-loaded data — no additional API call is made.

## Chart detail

| Element     | Description                                       |
| ----------- | ------------------------------------------------- |
| X-axis      | Datetime grouped hourly (format: Month/Day HH:00) |
| Y-axis      | Efficiency 0–100%                                 |
| Purple line | Selected Lamp 1 efficiency                        |
| Red line    | Selected Lamp 2 efficiency                        |
| Blue line   | Average efficiency of all 16 lamps                |

## Analysis sentence

Below the chart, an automatically generated sentence computes the percentage difference between the two lamps' most recent efficiency values. For example:

> "Lamp 5 is operating at 4.2% higher efficiency than Lamp 12 based on the latest data."

## Summary stat row

| Stat        | Description                                                    |
| ----------- | -------------------------------------------------------------- |
| Total Lamps | Always 16                                                      |
| Data Points | Number of telemetry records loaded for the selected date range |
| Time Period | Number of days in the selected range                           |

## Source

| Stage   | Endpoint                                                                |
| ------- | ----------------------------------------------------------------------- |
| Stage 1 | `/api/telemetry/aggregated?interval=day&startDate=...&endDate=...`      |
| Stage 2 | `/api/telemetry/chunked?startDate=...&endDate=...&offset=...&limit=500` |