Statistics 2126

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Statistics 2126

• Dr. Dave Brodbeck

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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

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Numbers and Reality

• You can do pretty much anything to numbers
• They dont complain
• Here is a batch of six numbers
• 33, 6, 2, 66, 12, 91
• The average of these numbers is 34

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Reality is overrated

• So the average is 34
• Is this meaningful?
• Well not so much in this case no

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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

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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

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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

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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)

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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.)

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Now for an audience participation number

• What type of variables are these?
• Speed
• Number of Stanley Cups won
• TV channel
• CIS football ranking
• IQ

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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

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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