Which method is considered the most reliable for estimating physical activity according to researchers?

The most reliable method for estimating physical activity, according to researchers, involves combined approaches. This is because no single method captures the entirety of an individual’s physical activity levels accurately on its own.

When using self-reported data, there is often a risk of bias, as individuals may overestimate or underestimate their activity levels due to recall bias or social desirability. Direct observation can provide accurate data but is often limited by its practicality. Observers can only assess activity in the specific environments where they are present, which may not represent a person's overall activity.

Wearable technology offers benefits by providing continuous, objective measures of activity throughout the day. However, the reliance solely on this technology may miss contextual information such as intensity or the type of activities being performed in certain social situations.

Combining these methods—self-reporting, direct observation, wearable technology, and even physical fitness assessments—allows for a more comprehensive picture of a person's physical activity. This approach capitalizes on the strengths of each method, enhancing the overall reliability and validity of the activity estimation. Hence, combined approaches stand out as the most effective for accurately understanding an individual's physical activity levels.