Which sampling method is less likely to have observer bias?

Systematic sampling is less likely to have observer bias because it involves a predetermined method for selecting samples from a population. This approach typically applies a consistent criteria or interval, allowing researchers to collect data in a structured manner. By following a specific pattern—for example, selecting every fifth sample or using fixed intervals—systematic sampling minimizes the influence of an observer's subjective judgment or preference when determining which samples to collect.

In contrast, random sampling, while it does aim for an unbiased representation, can still introduce bias based on how the randomization is executed. If the method of randomization is flawed or poorly implemented, it may not fully eliminate bias. Intuitive sampling relies significantly on the observer's personal judgment, making it particularly susceptible to observer bias. Thus, systematic sampling provides a more reliable method to gather data with reduced potential for bias.