2-3: Measures of Central Tendency

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# 2-3: Measures of Central Tendency - PowerPoint PPT Presentation

2-3: Measures of Central Tendency. A typical, or central entry of a data set. MEAN: average µ=population mean = Σ x/N =sum of data÷population x = sample mean = Σ x/n = sum of data ÷ sample MEDIAN: middle put in numerical order Find middle #, or add 2 middle #’s &amp; ÷ 2

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Presentation Transcript
2-3: Measures of Central Tendency
• A typical, or central entry of a data set.
• MEAN: average

µ=population mean = Σx/N =sum of data÷population

x = sample mean = Σx/n = sum of data ÷ sample

• MEDIAN: middle

put in numerical order

Find middle #, or add 2 middle #’s & ÷ 2

• MODE: most frequent
Find the mean, median & mode

500 840 470 480 420 440 440

500 840 470 480 420 440

Mean

Median

Mode

• Mean
• Median
• Mode
Find the mean, median & mode

500 840 470 480 420 440 440

500 840 470 480 420 440

Mean

500+840+470+480+420+440 =

3150

3150/6 = 525

Median

Mode

• Mean

500+840+470+480+420+440+ 440 = 3590

3590/7 = 512.857 ≈ 513

• Median
• Mode
Find the mean, median & mode

500 840 470 480 420 440 440

500 840 470 480 420 440

Mean

500+840+470+480+420+440 =

3150

3150/6 = 525

Median

420 440 470 480 500 840

2 mids: 470 +480 =950/2=475

Mode

• Mean

500+840+470+480+420+440+ 440 = 3590

3590/7 = 512.857 ≈ 513

• Median

420 440 440 470 480 500 840

middle entry is 470

• Mode
Find the mean, median & mode

500 840 470 480 420 440 440

500 840 470 480 420 440

Mean

500+840+470+480+420+440 =

3150

3150/6 = 525

Median

420 440 470 480 500 840

2 mids: 470 +480 =950/2=475

Mode: none

• Mean

500+840+470+480+420+440+ 440 = 3590

3590/7 = 512.857 ≈ 513

• Median

420 440 440 470 480 500 840

middle entry is 470

• Mode: 440 occurs most
Measures of Central Tendency
• Bimodal: If 2 numbers occur MOST frequently. 2 modes exist
• Outlier: A data entry very far away from all the other data. Can affect the mean. Sometimes outliers are removed from data before computing central tendencies.