Question

A business consultant for the National Transportation Safety Board (NTSB), collected data on the safety of hybrid automobiles traveling at 30, 40 and 50 miles per hour.  She randomly assigned the same hybrid model to each condition and collected data on the pressure applied to the driver’s head during a crash into a wall at each speed.

What is the independent variable? Dependent variable?

Is she able to make cause and effect statements about the cars the head pressure? Explain.  Give a hypothetical cause and effect statement.

Assume for a moment that she randomly selected 9 hybrids from the thousands of hybrids produced by the manufacturer.  Is she able to generalize to all automobiles produced by that manufacturer? Explain.

Answer 1

(i)

The independent variable is speed of hybrid automobiles during a crash into a wall

(ii)

Dependent variable : pressure applied to the driver’s head during a crash into a wall

(iii)

She is able to make cause and effect statements about the cars the head pressure because she collected data on the pressure applied to the driver’s head during a crash into a wall at each speed. A hypothetical cause and effect statement is as follows:

The increase in the speed of hybrid automobiles during a crash into a wall causes corresponding increase in the pressure applied to the driver’s head during a crash into a wall

(iv)

She is not able to generalize to all automobiles produced by that manufacturer because factors other than the speed of hybrid automobiles during a crash into a wall which causes the pressure applied to the driver’s head, confounding variables such as road condition, traffic congestion, driver's condition: whether he is drunk, etc., are not controlled in this experimentation.