CLS Research Methodology & Design 2

Question 1

Which study design is most appropriate for establishing a causal relationship between laser treatment parameters and clinical outcomes?

Accepted Answer

Randomized controlled trial

Answer

Randomized controlled trials (RCTs) are the gold standard for establishing causation. Random assignment of participants to treatment and control groups eliminates selection bias and allows researchers to attribute outcome differences to the intervention.

Question 2

In a laser efficacy study, what is the primary purpose of a washout period between treatment phases in a crossover design?

Accepted Answer

To allow carryover effects from the previous treatment to dissipate

Answer

A washout period ensures that any residual effects from the first treatment phase have resolved before the participant crosses over to the next treatment. This prevents carryover effects from confounding comparisons between treatments.

Question 3

Which measurement scale is most appropriate for recording a patient's subjective pain level during laser treatment on a scale of 0 to 10?

Accepted Answer

Interval

Answer

Pain scales like the Numeric Rating Scale (NRS 0–10) are treated as interval scales, where equal distances between numbers represent equal differences in pain intensity and a true zero indicates complete absence of pain, making ratio properties applicable as well.

Question 4

A laser study reports a p-value of 0.03. What does this indicate?

Accepted Answer

There is a 3% probability of observing results this extreme if the null hypothesis is true

Answer

A p-value of 0.03 means there is a 3% probability of obtaining the observed results (or more extreme) purely by chance if the null hypothesis (no effect) were true. It does not directly measure the probability that the treatment works or the size of the effect.

Question 5

What is blinding in the context of a laser treatment clinical trial?

Accepted Answer

Preventing participants and/or evaluators from knowing group assignment

Answer

Blinding (masking) prevents knowledge of group assignment (treatment vs. control) from influencing participant responses or evaluator assessments. Double-blinding, where both participants and outcome assessors are blinded, reduces bias most effectively.

CLS - Certified Laser Specialist Practice Test

CLS - Certified Laser Specialist Practice Test

CLS Research Methodology & Design 2