Sample Size Overview

Flashcards to help review key concepts about sample size in research studies.

What is the general rule regarding sample size in research?

The larger the sample size, the better is often stated, but a smaller sample can be adequate if it meets study goals.

What does a larger sample size help reduce in studies?

A larger sample size helps reduce sampling error and upholds ethical principles.

What is an important consideration when estimating sample size in longitudinal studies?

Longitudinal studies typically require larger samples than cross-sectional studies due to potential attrition.

When is a larger sample size necessary regarding confidence levels?

A larger sample size is needed for a higher level of confidence, such as 95%, compared to lower levels like 80%.

What should be considered when comparing two population proportions?

Factors such as confidence level, statistical power, and rate of outcome in the unexposed group are critical.

What is the formula for computing sample size when estimating a population proportion?

n = Z^2PQ/d^2 where Z is the reliability of the estimate corresponding to a set level of significance.

What kind of design requires a larger sample size: cluster sampling or simple random sampling?

Cluster sampling designs generally require larger samples than simple random sampling designs.

How does the nature of variability affect sample size requirements?

More heterogeneous populations require larger sample sizes to accurately estimate parameters.

What is a key takeaway regarding sample size calculations and ethics?

Increasing sample size too much may expose participants to ineffective treatments, raising ethical concerns.

What does a sufficient sample size provide in terms of statistical power?

It enhances the study's ability to detect a difference, typically set at 80% for many studies.