What type of study was used in the left-handed versus right-handed mortality investigation?

The investigation on left-handed versus right-handed mortality utilized an observational study design. In an observational study, researchers observe participants and measure variables without manipulating any factors or assigning treatments. This means that the researchers look at existing differences between groups—in this case, left-handed and right-handed individuals—without intervening or altering any conditions.

In the context of studying mortality among left- and right-handed individuals, researchers likely collected data from various sources, such as health records or demographic surveys, to identify patterns or outcomes related to mortality based on handedness. Since the researchers did not experiment with or control the handedness of individuals, this confirms that the investigation relied on observation of naturally occurring behaviors and outcomes.

This method allows researchers to identify correlations and trends while being careful about inferring causation. The objective in such studies is to gather insights based on real-world data, making observational studies particularly useful in assessing the impact of factors like handedness on mortality rates.