# Performance & Stability Scoring ## Overview When evaluating providers, you often want to balance raw performance (for example, speed) with consistency (low variability). A provider with the fastest average latency but frequent spikes might not be the best choice for latency-sensitive applications. Provider Intelligence offers a **Performance & Stability** score that combines both components in an approach that ensures that providers with higher scores in both areas are advantaged over providers with only one high score. {% hint style="info" %} The combined Performance & Stability score does not appear on the results page; it feeds directly into the overall score when you choose Performance & Stability as your results calculation mode. {% endhint %} ## Comparing Averages A simple average (arithmetic mean) can artificially inflate combined scores when one component is high and the other is low. We use a kind of average (harmonic mean) that advantages higher component scores and penalizes providers where one component is high and the other low. ### Why Harmonic Mean Is Better * You want providers that are both fast and consistent. * A provider that's very fast but unpredictable isn't a good choice. * A provider that's very consistent but slow isn't a good choice either. * The harmonic mean ensures you prioritize providers that are strong in both areas. See [Specify Results Calculation](https://docs.thousandeyes.com/product-documentation/internet-insights/provider-intelligence/build-a-query/specify-results-calculation) to understand when to choose **Performance & Stability** scoring vs. **Performance** only scoring in your overall score calculation. ## Harmonic Mean Calculation and Example Understanding the harmonic mean is best understood in relation to the arithmetic mean. 1. **Arithmetic Mean**: An arithmetic mean for 2 numbers (X and Y) is their sum divided by 2. For example, if the performance score is 95 and the stability score is 50, the simple average is (95 + 50)/2 = 72.5. 2. **Harmonic Mean**: A harmonic mean *multiplies* X by Y and then by 2, before dividing by their sum. In this way, any *difference* between the two values pulls the final score more towards the lower of the two, penalizing the difference. In the example above, the harmonic mean for 95 and 50 is instead 95 \* 50 \* 2/(95 + 50) = 65. While the simple average treats both scores equally and can be pulled up by a high score, the harmonic mean is more sensitive to the lower score. This means if one score is significantly lower, the harmonic mean is closer to that lower value, effectively reducing the combined score to reflect the weaker aspect. ### Comparison Example | Provider | Performance Score | Stability Score | Simple Average | Harmonic Mean | | ---------- | ----------------- | --------------- | -------------- | ------------- | | Provider 1 | 90 | 90 | 90 | 90 | | Provider 2 | 95 | 50 | 72.5 | 65 | | Provider 3 | 70 | 70 | 70 | 70 | **Interpretation**: Provider 2 has excellent raw performance (95) but poor stability (50). The simple average (72.5) suggests Provider 2 is better than Provider 3 (70), but this ignores the instability. The harmonic mean (65) corrects this by penalizing Provider 2 for inconsistency. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.thousandeyes.com/product-documentation/internet-insights/provider-intelligence/scoring-methodologies/performance-and-stability-scoring.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.