Screen-dialog flows are sequences of screens and dialogs that represent the user interface and interaction of a system. Use case testing is a technique that uses use cases as a test basis to derive test cases1. A use case is a description of interactions between actors and a system to achieve a goal1. Use case testing is the most effective technique in testing screen-dialog flows, as it can capture the user requirements, scenarios, and expected outcomes of the system. Boundary value testing is a technique that uses boundary values as a test basis to derive test cases1. A boundary value is an input value or output value on the edge of an equivalence partition or at the smallest or largest value of a range1. Boundary value testing is not the most effective technique in testing screen-dialog flows, as it is more suitable for testing numerical inputs and outputs. Statement testing and coverage is a technique that uses statements in the source code as a test basis to measure the coverage achieved by a test suite1. A statement is a minimal executable unit of source code1. Statement testing and coverage is not the most effective technique in testing screen-dialog flows, as it is more suitable for testing the internal logic and structure of the code. State transition testing is a technique that uses state transition diagrams as a test basis to derive test cases1. A state transition diagram shows the states of a system and the transitions between them triggered by events or conditions1. State transition testing is not the most effective technique in testing screen-dialog flows, as it is more suitable for testing systems that have complex or dynamic behavior based on different states.