Stated Preference techniques are used to figure out how much people value different aspects of transportation systems. Some things, like cost and travel time, are easy to understand and put a price on. But other things, like how reliable a journey is or how nice the ride is, are harder to measure. A study on the Manchester LRT system found that how these attributes are presented to people can change the results of the research. Showing information in words versus pictures can make a big difference in how people value different aspects of transportation.