Equation 12 · Part 8 · Why Average Success Rate Hides the Failures That Matter Most

Starting index or lower bound: i

R = \sum_{i} \Pr(\text{failure mode } i) \cdot B_i

i

What this part means

This label says where the repeated addition, multiplication, or accumulation starts. Read its value or condition together with the article’s description of the index.

Its job in the formula

i appears in the bound of this sum. The bound states where the repeated operation starts, ends, or which values it includes.

Full expressionStarting index or lower bound: iArticle meaning

The passage around this formula

…deleted database as the same unit. A more defensible score weights each discovered failure mode by its consequence rather than counting it once: $R = \sum_{i} \Pr(\text{failure mode } i) \cdot B_i$ . where $B_i$ is the blast radius assigned to failure mode i : how much of a system, how much data, how many users or how much liability a given failure could plausibly reach, drawn from a small number of severity tiers rather than treated as a continuous unknown. This is not a hypothetical scoring scheme; tiered, severity-weighted evaluation of exactly…

Read this part in the article →

Learn the underlying idea

Σ adds a collection of terms. Π multiplies them. The lower and upper labels tell you which terms belong to the collection.

Open the illustrated sums and products: repeat an operation over an index guide →

See this notation across published equations →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.