Enum ViolationType 

pub enum ViolationType {
    BeyondLimits,
    NineOneSide,
    SixTrend,
    FourteenAlternating,
    TwoOfThreeBeyond2Sigma,
    FourOfFiveBeyond1Sigma,
    FifteenWithin1Sigma,
    EightBeyond1Sigma,
    EightOneSide,
}

Types of control chart violations: Nelson’s eight tests, and the Western Electric run rule where it differs from Nelson’s.

Each variant is one test for special causes of variation, and its name is the name it goes by on the wire.

Reference

Nelson, L.S. (1984). “The Shewhart Control Chart — Tests for Special Causes”, Journal of Quality Technology 16(4), pp. 237-239. Western Electric (1956). Statistical Quality Control Handbook.

Variants

BeyondLimits

Point beyond control limits (Nelson Rule 1).

A single point falls outside the 3-sigma control limits.

NineOneSide

9 points in a row on same side of center line (Nelson Rule 2).

Indicates a sustained shift in the process mean.

SixTrend

6 points in a row steadily increasing or decreasing (Nelson Rule 3).

Indicates a trend in the process.

FourteenAlternating

14 points in a row alternating up and down (Nelson Rule 4).

Indicates systematic variation (e.g., two alternating streams).

TwoOfThreeBeyond2Sigma

2 out of 3 points beyond 2 sigma on same side (Nelson Rule 5).

An early warning of a potential shift.

FourOfFiveBeyond1Sigma

4 out of 5 points beyond 1 sigma on same side (Nelson Rule 6).

Indicates a small sustained shift.

FifteenWithin1Sigma

15 points in a row within 1 sigma of center line (Nelson Rule 7).

Indicates stratification — reduced variation suggesting mixed streams.

EightBeyond1Sigma

8 points in a row beyond 1 sigma on either side (Nelson Rule 8).

Indicates a mixture pattern — points avoid the center zone.

EightOneSide

8 points in a row on same side of center line (Western Electric rule 4).

The Western Electric handbook’s run rule; Nelson’s Rule 2 (NineOneSide) asks for nine.

Implementations

impl ViolationType

pub const ALL: [ViolationType; 9]

Every test: Nelson’s eight in his numbering, then Western Electric’s run rule.

pub fn name(self) -> &'static str

The name a point’s violations and a request’s rules use for this test.

pub fn from_name(name: &str) -> Option<Self>

The test a name stands for.

Trait Implementations

impl Clone for ViolationType

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ViolationType

impl Debug for ViolationType

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for ViolationType

impl FromIterator<ViolationType> for RuleSet

fn from_iter<I: IntoIterator<Item = ViolationType>>(iter: I) -> Self

Creates a value from an iterator.

impl PartialEq for ViolationType

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ViolationType