1.1. To identify the independent variable in an investigation, we should focus on the variable that is controlled or manipulated to observe its effect on another variable.
In this investigation, the factor being manipulated is altitude. The scientist measures the average number of red blood cells for people living at different altitudes. This implies that the values for altitude are set by the researcher to study the resulting changes in the average number of red blood cells.
Thus, the independent variable of this investigation is:
- Altitude (m)
The altitude, measured in meters, is the variable that is controlled during the experiment to observe its influence on the dependent variable, which in this case is the average number of red blood cells.
