Lecture 11 - Data Analysis

Question 1

Descriptive Statistics

3 parts

L11, P.1

Answer 1

• Used to summarize/describe/analyze data
  1. Measures of central tendancy
  2. Measures of variation
  3. Measures of Association

Question 2

Measures of Central Tendancy

L11, P.2

Answer 2

• Include the Mode, Median and Mean

Question 3

Mode

L11, P.2

Answer 3

• A measure of central tendancy
• Is the most frequently occuring value in a set of scores
• Examples that =3
  1. Data Set = 1, 3, 3, 3, 4, 5
  2. Data Set = 3, 3, 3, 9, 10, 10
• Both equal 3 since it occurs 3/6 times in the data set

Question 4

Median

L11, P.2

Answer 4

• A Measure of central tendancy
• The middle number in a set of scores that have been ranked in numerical order
• Examples that = 3
  1. Data Set = 1, 1, 1, 1, 3, 5, 5, 5, 5
  2. Data Set = 1, 2, 2, 2, 3, 4, 4, 4, 5
• Half the scores fall below the median and half the scores fall above
• Favoured when there are rare but extreme score(s) in a data set

Question 5

Mean

L11, P.2-3

Answer 5

• A measure of central tendancy
• The artithmetic average of a set of scores
• Most common measure used in statistical analysis
• Tells us more about the broader data set than both the median and mode
• Ex. (below)
• Data Set = 1, 1, 1, 1, 5, 5, 1, 1,
• 1 + 1 + 1 + 1 + 5 + 5 +1 +1 = 16 (total of all numbers in the data set) divided by 8 (amount of numbers in data set) = 2

Question 6

Measures of Variability

3 Types

L11, P.3

Answer 6

• A measure of varaiation
• Tells us something about how spread out scores in a data set are
• Includes Range, Variance and Standard Deviation

Question 7

Range

L11, P.3

Answer 7

• What is the difference between the largest and smallest score in a data set
• Not used often
• Ex (below)
• Data Set = 1, 4, 2, 4, 5, 4, 3, 2
• Found by subtracting the smallest number in the data set from the largest (5-1=4)

Question 8

Variance

L11, P.3

Answer 8

• A measure of variability
• The average squared deviation from the means of scores in a group
• Ex (below)
• Data Set = 1, 2, 3, 4, 5
  1. Subtact the mean from all numbers in the data set (-2, -1, 0, 1, 2)
  2. Square all deviation scores and add together (4 + 1 + 0 + 1 + 4 = 10)
  3. Divide the sum of all deviations by the number of scores (10 divided by 5 = 2

Question 9

Standard Deviation

(SD)

L11, P.4

Answer 9

• A measure of variation
• = variance squared
• Ex (below)
• Variance = 2
• 2 squared is 1.4 (1.4 is the SD)

Question 10

Measures of Association