In performance testing, a realistic workload model must simulate the behavior of actual users. The total time for a user to complete an interaction cycle consists of two main components: the system's response time to a request and the time the user pauses before initiating the next request. This pause, which represents the user reading the screen or deciding on the next action, is known as think time. Therefore, to accurately model the total time and throughput of user transactions, think time must be included in test scripts in addition to measuring the transaction response time.

B. Wait time: This term is ambiguous. It can refer to time spent in a server-side queue (which is part of the response time) or be used as a general term for any delay. "Think time" is the precise, industry-standard term for the simulated user pause between transactions.

C. Action time: This is not a standard term in performance testing. The time taken by the client to send a request is typically negligible or considered part of the overall transaction response time.

D. User time: This term is too general and is not a specific, measurable metric used in the context of performance test scripting and analysis.

1. ISTQB® Certified Tester

Performance Testing Syllabus (2018):

Section 3.2.2

Workload: "The workload model should also include think times. Think time is the time that a real user would take between receiving a response from one request and submitting the next request."

Glossary

p. 49: "Transaction response time: The time that elapses from the moment a user executes a request until the response for that request has been received by the user."

URL: https://www.istqb.org/certifications/performance-testing (Link to the official page where the syllabus can be downloaded).

2. ISTQB® Certified Tester

Advanced Level Syllabus

Test Analyst (2019):

Section 4.3.2

Performance Test Execution: "The think time is the time a user is expected to wait between transactions. For example

a user may read a page for 30 seconds before clicking the next link. This is the think time."

URL: https://www.istqb.org/certifications/test-analyst (Link to the official page where the syllabus can be downloaded).

3. Jain

R. (1991). The Art of Computer Systems Performance Analysis: Techniques for Experimental Design

Measurement

Simulation

and Modeling. Wiley.

Chapter 3

Section 3.3

Types of Workloads: This foundational text discusses the components of a workload

including the requests sent to a system and the timing between them

establishing the concept of think time as a critical parameter for realistic load simulation. (While a general reference

it underpins the principles used in the ISTQB syllabus).