1. Statistics 2126 Dr. Dave Brodbeck

2. Introduction What is statistics? Why is it useful? –We are all consumers of scientific information –Political polls –“A recent study showed….” –Allows us to determine if something “really” happened –And it is a required course…

3. Numbers and Reality You can do pretty much anything to numbers They don’t complain Here is a batch of six numbers: 33, 6, 2, 66, 12, 91 The average of these numbers is 34

4. Reality is overrated So the average is 34 Is this meaningful? Well not so much in this case no…

5. Variables A variable is a measurable factor, characteristic, or attribute of an individual or a system In other words, stuff you can measure Age Height Eye colour

6. Levels of measurement Variables can be classified as to their level of measurement Nominal variables are basically categories e.g –Hair colour –Hockey sweater number

7. More variables Ordinal variables represent not only category but order So like first, second and third place in a race The difference is not consistent though

8. Very nice variables With interval variables the distance between the values is meaningful 25 ºC 5 ºC warmer than 20 ºC 275 ºC 5 ºC warmer than 270 ºC However, 20 ºC is NOT twice as warm as 10 ºC There is no real zero point (0 ºC does not represent no temperature)

9. Ratio scales are the very best The ratio scale brings in all of the other characteristics discussed so far, but brings in a true 0 point Kelvins 20 K IS twice as warm as 10 K (still pretty freaking cold though….)

10. Now for an audience participation number What type of variables are these? Speed Number of Stanley Cups won TV channel CIS football ranking IQ

11. More stuff you should know Operational definition –Defining a construct solely based on the operations used to measure it Intelligence is IQ Hungry is not having eaten for 5 hours How about –Tired –Rich –Runs fast

12. More Key Terms Distribution –What values variables take under what conditions Variables can be either discreet or continuous Discreet variables –Different values, but only some Continuous variables –Infinite number of values