Statistics

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Statistics - PowerPoint PPT Presentation

Statistics. Entering numeric data. On your iclicker. You will be told when a numeric input is required Use the “up and down” arrow keys at the top to increase or decrease the number. Use the “left and right” arrow keys to move the cursor.

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PowerPoint Slideshow about 'Statistics' - irma

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Presentation Transcript
Entering numeric data
• You will be told when a numeric input is required
• Use the “up and down” arrow keys at the top to increase or decrease the number.
• Use the “left and right” arrow keys to move the cursor.
• Press “send” when you have entered the desired answer.
Trial run
• Starting now, enter a number in your head between 0 and 99.
• Press send when you are done.
Clicker question
• Enter your height to the nearest inch.
• For example if your height is 5’10” then enter 5*12+10=70.
Clicker Q version 2
• Enter which range your height falls in:
• A) < 5’00” B)5’00-5’04”
• C) 5’5”-5’10” D) 5’11”-6’3”
• E) > 6’3”
What does the mean mean?
• Numbers x1 ,…, xN their mean value is their sum divided by N
What is the mean height of an American president?
• X: a president’s height. Its values are:
• 64,66,66,67,67,67,68,68,68,68,68.5,69,69,69.5,70,70,70,70,70.5,71,71,71,71,71.5,72,72,72,72,72,72,72,72,73,73,74,74,74,74,74.5,74.5,75,76
• N=42
• Mean=(64+2x66+3x67+4x68+68.5+2x69+69.5+5x70+70.5+4x71+71.5+8x72+2x73+4x74+2x74.5+75+76)/42=70.69
Obama is 6'1 (73 inches) and tied with Andrew Jackson and Ronald Reagan for 9th tallest president.
What does the mean miss?
• Two random variables are correlated if an increase in one corresponds to an increase in the other.
• For example, tall people, on average, weigh more.
• Average height of a human, on average, has increased with time.
What does the median mean?
• Given numbers x1 ,…, xN their MEDIAN is the number that is less than half the numbers and greater than half the numbers.
• If there is an even number of samples, the mean is usually the average of the two middle values.
• What is the median height for a U.S. president?
Mean and median household incomes
• Compute the mean household income based on the data above
• Compute the median based on the data above.
Variance
• The variance of numbers x1 ,…, xN is the sum of the squares of their differences from their mean, divided by N-1.
• The sample deviation is the square root of the variance.
Covariance
• Covariance is a measure of how much two variables vary together.
Formula for BMI
• BMI=Mass (kg)/(Height(m))^2
• =(weight(lb)/(height (in)^2)*703
Clicker question
• What is your BMI (round to the nearest whole number). Enter as numerical input.

Height: 5'9" (175 cm)

• Olympic Weight: 203 lbs (92 kg)
• BMI=92/(1.75)^2 =30.04
Are tall people smarter?
• How tall is Randy Newman?
• Height and intelligence
• Why are tall people smarter?
• Height and income
• Height, income and intelligence
• Best revenge is living long
Health statistics
• The Centers for Disease Control web site has a lot of data on various health statistics for the U.S.
• Example: Is obesity a problem in the U.S.?
Exercises
• Compute the average height, average weight, median height, median weight, variance of the heights, and variance of the weights from the following datatakn from the following source
• Heights and weights data
Exercise 2
• For each individual in the previous table, compute the BMI of that individual.
Exercise 3
• For each of the Olympic athletes in the following table taken from fatchic compute the athlete’s BMI.
• What are the average heights and weights for the athletes?
• What is the variance in heights and weights of these athletes?