Mean (Average): The sum of all numbers divided by the count of numbers
Median: The middle number when data is arranged in order from least to greatest
Mode: The number that appears most frequently in a data set
Range: The difference between the highest and lowest numbers in a data set
Data Set: A collection of numbers or information to analyze
Statistical Measure: A number that describes a characteristic of a data set
- Add: Add all numbers in the data set
- Count: Count how many numbers there are
- Divide: Divide the sum by the count
- Round: Round to the nearest whole number if needed
- Order: Arrange numbers from least to greatest
- Count: Determine how many numbers there are
- Find Middle: If odd count, pick middle number; if even count, average the two middle numbers
- Count: Count how many times each number appears
- Compare: Find the number that appears most often
- Identify: The most frequent number is the mode
- Order: Arrange numbers from least to greatest
- Identify: Find the highest and lowest numbers
- Subtract: Highest - Lowest = Range
• Mean sensitivity: Affected by very large or small numbers
• Median stability: Not affected by extreme values
• Mode existence: May not exist if all numbers appear equally
• Range simplicity: Only depends on highest and lowest values
Basic Statistics: Calculating all four measures for a simple data set to understand the fundamentals.
- Mean: Add all numbers and divide by count
- Median: Order numbers and find middle value
- Mode: Count frequency of each number
- Range: Subtract lowest from highest
Add all numbers: 6 + 8 + 10 + 12 + 14 + 8 + 6 = 64
Count numbers: 7
Mean = 64 ÷ 7 ≈ 9.1
Order numbers: 6, 6, 8, 8, 10, 12, 14
With 7 numbers (odd), median is the middle (4th) number
Median = 8
Count frequencies: 6(2 times), 8(2 times), 10(1 time), 12(1 time), 14(1 time)
Both 6 and 8 appear most often (2 times each)
Mode = 6 and 8 (bimodal)
Highest value: 14
Lowest value: 6
Range = 14 - 6 = 8
Mean ≈ 9.1, Median = 8, Mode = 6 and 8, Range = 8
• Multi-measure analysis: Calculate all four measures for complete picture
• Data organization: Ordering helps with median and range calculation
• Context interpretation: Each measure provides different insight
• Multiple modes: When two values tie for most frequent
Intermediate Statistics: Working with slightly larger data sets to practice all four statistical measures.
Add all numbers: 15 + 18 + 21 + 24 + 27 + 18 + 21 + 21 = 165
Count numbers: 8
Mean = 165 ÷ 8 = 20.625 ≈ 20.6
Order numbers: 15, 18, 18, 21, 21, 21, 24, 27
With 8 numbers (even), median is average of 4th and 5th numbers
Median = (21 + 21) ÷ 2 = 21
Count frequencies: 15(1), 18(2), 21(3), 24(1), 27(1)
Number 21 appears most often (3 times)
Mode = 21
Highest value: 27
Lowest value: 15
Range = 27 - 15 = 12
Mean ≈ 20.6, Median = 21, Mode = 21, Range = 12
• Even count median: Average the two middle numbers
• Single mode: One value appears most frequently
• Range independence: Only affected by extreme values
Uniform Distribution: When all values in a data set are identical, all measures of center are the same value.
Add all numbers: 9 + 9 + 9 + 9 + 9 = 45
Count numbers: 5
Mean = 45 ÷ 5 = 9
Order numbers: 9, 9, 9, 9, 9
With 5 numbers (odd), median is the middle (3rd) number
Median = 9
Count frequencies: 9(5 times)
Number 9 appears most often (5 times)
Mode = 9
Highest value: 9
Lowest value: 9
Range = 9 - 9 = 0
Mean = 9, Median = 9, Mode = 9, Range = 0
• Uniform distribution: All measures equal the common value
• Zero range: When all values are identical
• Single mode: When all values are the same
Outlier Effect: When a data set has extreme values (outliers), it affects the mean more than the median.
Add all numbers: 3 + 6 + 9 + 12 + 15 + 18 + 100 = 163
Count numbers: 7
Mean = 163 ÷ 7 ≈ 23.3
Order numbers: 3, 6, 9, 12, 15, 18, 100
With 7 numbers (odd), median is the middle (4th) number
Median = 12
Count frequencies: 3(1), 6(1), 9(1), 12(1), 15(1), 18(1), 100(1)
All numbers appear once
Mode = none
Highest value: 100
Lowest value: 3
Range = 100 - 3 = 97
Mean ≈ 23.3, Median = 12, Mode = none, Range = 97
• Outlier effect: Extreme values pull the mean away from the center
• Median stability: Less affected by outliers than the mean
• No mode: When all values appear equally
Multi-Modal Distribution: When multiple values share the highest frequency, creating multiple modes.
Add all numbers: 12 + 14 + 16 + 18 + 20 + 14 + 16 + 18 + 16 + 14 = 158
Count numbers: 10
Mean = 158 ÷ 10 = 15.8
Order numbers: 12, 14, 14, 14, 16, 16, 16, 18, 18, 20
With 10 numbers (even), median is average of 5th and 6th numbers
Median = (16 + 16) ÷ 2 = 16
Count frequencies: 12(1), 14(3), 16(3), 18(2), 20(1)
Both 14 and 16 appear most often (3 times each)
Mode = 14 and 16 (bimodal)
Highest value: 20
Lowest value: 12
Range = 20 - 12 = 8
Mean = 15.8, Median = 16, Mode = 14 and 16, Range = 8
• Multi-modal analysis: Count all frequencies to find the mode
• Even count median: Average the two middle values
• Comprehensive view: All four measures provide complete data picture