changes

crates/domain/src/correlation/p_value.rs

@@ -0,0 +1,29 @@
+use crate::errors::DomainError;
+
+use super::normal::two_sided_tail;
+
+const CERTAIN: f64 = 1.0;
+const IMPOSSIBLE: f64 = 0.0;
+
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
+pub struct PValue(f64);
+
+impl PValue {
+    pub fn new(value: f64) -> Result<Self, DomainError> {
+        if !value.is_finite() || !(IMPOSSIBLE..=CERTAIN).contains(&value) {
+            return Err(DomainError::InvalidInput(format!(
+                "a p-value must be between {IMPOSSIBLE} and {CERTAIN}, got {value}"
+            )));
+        }
+
+        Ok(Self(value))
+    }
+
+    pub fn from_standard_score(standard_score: f64) -> Self {
+        Self(two_sided_tail(standard_score))
+    }
+
+    pub fn value(&self) -> f64 {
+        self.0
+    }
+}