Which of the following is an advantage of sequential design: it is usually very inexpensive it can be used to examine possible cohort effects it protects against possible practice effects O it does not require approval from an Institutional Review Board

The correct advantage of a sequential design is: **It can be used to examine possible cohort effects.** **Explanation:** Sequential designs combine elements of both cross-sectional and longitudinal studies. This approach allows researchers to examine age-related changes while controlling for cohort (generation) effects. By studying multiple cohorts over different time periods, sequential designs help differentiate whether observed differences are due to aging processes or specific characteristics of the cohorts being studied. **Why the other options are less appropriate:** - **It is usually very inexpensive:** Sequential designs are generally more resource-intensive than purely cross-sectional studies because they involve multiple cohorts and repeated measurements over time. - **It protects against possible practice effects:** While sequential designs can help identify cohort and age effects, they don't inherently protect against practice effects, which are improvements in test performance due to repeated exposure. - **It does not require approval from an Institutional Review Board:** This is incorrect. All research involving human participants typically requires approval from an Institutional Review Board (IRB) to ensure ethical standards are met. **Answer:** It can be used to examine possible cohort effects