Measurements and Uncertainty

SPEAKER 1: In this chapter, we lookedat how to plan a piece of research,how to make decisions about which variables to measure,and how to measure them.

SPEAKER 2: Our choice of which variables to measuregoes hand-in-hand with our research questionand hypothesis.There will be specific variables that we are interested in.Choosing how to measure them is something we must alwaysgive some more thought to.

SPEAKER 1: Decisions about how to measurevariables are essentially about what type of variable to use,interval, ordinal, or categorical, and, given that,what categories or scale to use.These decisions have small influenceson the uncertainty in our result.

SPEAKER 2: We need to decide what sort of informationis available about a variable.If we can only identify differences between people,then we use categories as values and a categorical variable.If we can place people in an order by the differences,then we use a scale for values and an interval or ordinalvariable.

SPEAKER 1: We make our measurementsso that they capture differences between people that mightmatter for our hypothesis.

SPEAKER 2: If we are using categories,make sure they are suitable ones.Variables where everyone has the same value are not helpful.Categories that end up empty are also not helpful.Choose categories that best representthe measured differences appropriately.

SPEAKER 1: And don't forget, if we are using scales,then we should make sure that the values we getare well distributed across the scale.For more information, see study.sagepub.com/statisticsforpsychology.