This page includes a description of the scoring algorithm used on the ECG Quiz, including a few exemplary cases to illustrate how the scoring algorithm works.

We believe people learning to analyze ECGs should practice finding every abnormality in a given ECG, just like they would when interpreting ECGs on the job. Experienced ECG readers develop a sequence that is used for every ECG:

1. Overall (degree and type of artifact, if any, and extent to which artifact may interfere with interpretation)
2. Rhythm (Is it regular? Can the P waves be seen? What is the relationship of the P waves to the QRS complexes?)
3. Intervals (rate, axis, PR interval, QRS duration, QT interval)
4. P wave morphology (width, height, and shape)
5. QRS complex morphology (duration, height, and shape)
6. Presence of pacemaker (which chambers, evidence of failure to capture and failure to sense properly)
7. Miscellaneous (everything not listed above).

In the old days, experienced ECG readers would gather for regular conferences to discuss interesting ECGs. As you can imagine, they would not always agree with each other. The reason is that while some features of ECGs are objective, others are subjective. For example, the presence of QRS complexes is objective. The presence of abnormalities in the shape of the T wave is sometimes subjective, especially the finding of “non-specific T wave abnormality.”

The ECG Quiz uses a sophisticated scoring algorithm to account for this “uncertainty” to give users meaningful analysis results. Our scoring algorithm categorizes the diagnoses assigned to a particular ECG as Must or Should based on the user-selected ECG interpretation skill level. For example, a Beginning Learner is expected to diagnose only “Supraventricular Tachycardia” when analyzing ECGs that exhibit that rhythm. On the other hand, an Intermediate Learner is expected to diagnose the mechanism of the tachyarrhythmia when the ECG contains clues, such as “Atrial Tachycardia,” “Junctional Tachycardia,” or “Sinus Tachycardia.” The Must and Should classification varies by skill level and the individual ECG being analyzed. Users get credit for a Should diagnosis included in their interpretation. However, the user is not penalized if they omit Should diagnoses when they are present.

In addition, the ECG Quiz implements a hierarchical diagnosis list where some diagnoses, such as “Atrial Flutter,” are further classified as “Atrial Flutter with 2:1 Ventricular Response” and “Atrial Flutter with Variable Ventricular Response.” More general diagnoses, such as “Atrial Flutter,” are higher in the diagnosis hierarchy than more specific diagnoses, such as “Atrial Flutter with Variable Ventricular Response.” Keep reading below to see how this mechanism allows users to use more specific diagnoses as their skills improve and receive credit for doing so.

When comparing your interpretation with our interpretation, each diagnosis entered by you and included in our interpretation is graded as one of the following:

True Positive (TP)

A diagnosis you include in your interpretation that is also in our interpretation

False Positive (FP)

A diagnosis you include in your interpretation that is not in our interpretation

False Negative (FN)

A Must diagnosis in our interpretation that you did not include in your interpretation

True Negative (TN)

A diagnosis you did not include in your interpretation that is not in our interpretation

Not Counted (NC)

A diagnosis that you included in your interpretation that is not counted as a result of hierarchical scoring (see below)

Duplicate Entry

A diagnosis included in your interpretation that is a duplicate of another diagnosis included in your interpretation.

Not Graded

A diagnosis included in your interpretation or the correct interpretation that was not used to grade your interpretation. ==== The Scoring Algorithm ====

For Must Diagnoses in our Interpretation

• If you include the diagnosis ⇒ True Positive (TP)
• If you fail to include the diagnosis and a more specific diagnosis on its hierarchy is included ⇒ Not Counted (NC)
• If you fail to include the diagnosis and do not include a more specific diagnosis on its hierarchy ⇒ False Negative (FN)

For Should Diagnoses in our Interpretation

• If you include the diagnosis ⇒ True Positive (TP)
• If you fail to include the diagnosis ⇒ Not Counted (NC)

For Diagnoses in your interpretation that are not in our Interpretation ⇒ False Positive (FP)

As mentioned above, the diagnosis list in the ECG Quiz is hierarchical, with more general diagnoses higher in the hierarchy and more specific diagnoses lower in the hierarchy. Using the hierarchy, the scoring algorithm modifies the grading of user interpretations based on three scenarios.

Scenario #1

Omitting a Must diagnosis that is in our interpretation and including a Should diagnosis that is in our interpretation that is in the hierarchy of the omitted Must diagnosis would be graded as follows:

• The missing Must ⇒ Not Counted
• The correct Should ⇒ True Positive

For example, consider an ECG exhibiting “Atrial Flutter with a 2:1 Ventricular Response.” At the “Beginning Learning” skill level, our interpretation will include “Atrial Flutter” as a Must diagnosis and “Atrial Flutter with 2:1 Ventricular Response” as a Should diagnosis. Entering “Atrial Flutter with 2:1 Ventricular Response” in your interpretation would be graded as a True Positive. Since “Atrial Flutter with 2:1 Ventricular Response” is in the hierarchy of “Atrial Flutter,” the “Atrial Flutter” Must diagnosis would be graded as a Not Counted even though you did not include it in your interpretation because you entered the more specific diagnosis!

Scenario #2

Omitting a Must diagnosis that is in our interpretation and including a diagnosis that is not in the Should list but is on the hierarchy of the Must diagnosis would be graded as follows:

• The omitted Must ⇒ True Positive
• The incorrect Should ⇒ False Positive

For example, consider the same ECG exhibiting “Atrial Flutter with a 2:1 Ventricular Response.” At the “Beginning Learning” skill level, our interpretation will include “Atrial Flutter” as a Must diagnosis and “Atrial Flutter with 2:1 Ventricular Response” as a Should diagnosis. Entering “Atrial Flutter with Variable Ventricular Response” in your interpretation would be graded as a False Positive because “Atrial Flutter with Variable Ventricular Response” is not in the Must or Should lists. However, since “Atrial Flutter with Variable Ventricular Response” is in the hierarchy of “Atrial Flutter,” the “Atrial Flutter” Must diagnosis would be graded as a True Positive. Hence, you are given credit (graded with a True Positive) for correctly identifying the Atrial Flutter but are penalized (graded with a False Positive) for not getting the correct, more specific diagnosis.

Scenario #3

Including a Must diagnosis that is in our interpretation and a Should diagnosis that is also in our interpretation that is on the hierarchy of the Must diagnosis would be graded as follows:

• The correct Must ⇒ Not Counted
• The correct Should ⇒ True Positive

The Must diagnosis is not counted because it is a more general term than the Should diagnosis.

As an example at the Beginner skill level, consider a narrow complex tachyarrhythmia that does not have visible P waves preceding the QRS complexes. Our interpretation will include “Supraventricular Tachycardia” as a Must diagnosis and “Junctional Tachycardia” as a Should diagnosis. If you include “Supraventricular Tachycardia” and “Junctional Tachycardia” in your interpretation, the “Junctional Tachycardia” would be graded as a True Positive, and the “Supraventricular Tachycardia” will not be counted because “Junctional Tachycardia” is more specific than “Supraventricular Tachycardia.” By scoring things this way, you get credit for the more specific diagnosis, but you do not get “double credit” for including both.

You may reread an ECG as often as you like. Your statistical summary will show how you have been doing with each interpretation of an ECG and with each diagnosis you encounter. In addition, you may reset your statistics whenever you like.

Good luck, and have fun!