diff --git a/README.md b/README.md
index 429e0e9b..164a1a19 100644
--- a/README.md
+++ b/README.md
@@ -761,6 +761,20 @@ Metric-specific subclasses:
 - [`LCPMetricWithAttribution`](/src/types/lcp.ts#:~:text=interface%20LCPMetricWithAttribution)
 - [`TTFBMetricWithAttribution`](/src/types/ttfb.ts#:~:text=interface%20TTFBMetricWithAttribution)
 
+#### `MetricThresholds`
+
+```ts
+/**
+ * The ranges defining a metric's "good", "needs improvement", and "poor"
+ * thresholds:
+ *
+ * - Metric values ≦ [0] are "good"
+ * - Metric values > [0] and ≦ [1] are "needs improvement"
+ * - Metric values > [1] are "poor".
+ */
+type MetricThresholds = [number, number];
+```
+
 #### `ReportCallback`
 
 ```ts
diff --git a/src/lib/bindReporter.ts b/src/lib/bindReporter.ts
index 0c2e2148..f3c42903 100644
--- a/src/lib/bindReporter.ts
+++ b/src/lib/bindReporter.ts
@@ -14,17 +14,12 @@
  * limitations under the License.
  */
 
-import {
-  Metric,
-  MetricRating,
-  MetricThresholds,
-  ReportCallback,
-} from '../types.js';
+import {Metric, MetricThresholds, ReportCallback} from '../types.js';
 
 const getRating = (
   value: number,
   thresholds: MetricThresholds
-): MetricRating => {
+): Metric['rating'] => {
   if (value > thresholds[1]) {
     return 'poor';
   }
diff --git a/src/types/base.ts b/src/types/base.ts
index 4c0a97b6..6550c133 100644
--- a/src/types/base.ts
+++ b/src/types/base.ts
@@ -19,12 +19,6 @@ import {
   NavigationTimingPolyfillEntry,
 } from './polyfills.js';
 
-/**
- * A rating indicating if a metric's value is within its "good", "needs
- * improvement", or "poor" thresholds.
- */
-export type MetricRating = 'good' | 'needs-improvement' | 'poor';
-
 /**
  * The ranges defining a metric's "good", "needs improvement", and "poor"
  * thresholds:
@@ -50,7 +44,7 @@ export interface Metric {
    * The rating as to whether the metric value is within the "good",
    * "needs improvement", or "poor" thresholds of the metric.
    */
-  rating: MetricRating;
+  rating: 'good' | 'needs-improvement' | 'poor';
 
   /**
    * The delta between the current value and the last-reported value.