Converting from the different levels of measurement

As a general rule, you can always transform a higher level of measurement to a lower level of measurement, but not the reverse. Often this is done via a technique known as binning in which you place all values with a certain range into a bin. You may want to take various ranges of height and bin them into tall, short, or medium based upon predefined ranges. However, you would generally not take a categorical variable and map it to a numeric variable, unless you knew a lot about how that category was measured and you were willing to make a lot of assumptions.