The blades are the most important part of a turbine: their design is crucial in capturing as much energy from the steam as possible and converting it into rotational energy by spinning the rotor round. All turbines have a set of rotating blades attached to the rotor and spin it around as steam hits them.
Gender variance is defined as the persistent sense that a person's gender identity is incongruent with the person's biological sex. The definition further excludes the element of persistence for persons under the age of 21 and including, without limitation, transitioned transsexuals.
Let's go once more to our study on IQ, but now let's say that we want to compare gender and IQ to see if girls are smarter than boys. Gender is a categorical variable, or a variable that involves two or more non-numeric groups. Gender is categorical because people are either male or female. Marital status is another categorical variable: a person can be married, single, divorced, widowed, and so on. Hair color, major, political affiliation, how depressed a person feels - all of these are categorical variables.