Lecture 3

Question 1

Central tendency

Answer 1

the tendency of data to cluster, or center, about certain numerical values

Question 2

variability

Answer 2

the spread of the data

Question 3

mean

Answer 3

the sum of observed values in a data set divided by the number of observations

Question 4

median

Answer 4

middle number when the measurements are arranged in ascending (or descending) order; if the number of observations is odd, then the sample median is the observed value exactly in the middle of the ordered list; if the number of observations is even, then the sample median is the number halfway between the two middle observed values in the ordered list

Question 5

mode

Answer 5

the most frequently occurring data element

Question 6

x with line over it

Answer 6

sample mean

Question 7

mu symbol

Answer 7

population mean

Question 8

M

Answer 8

sample median

Question 9

n with long tail

Answer 9

population median

Question 10

the sample mean is often use to estimate…?

Answer 10

the population mean

Question 11

the accuracy of using the sample mean to estimate the population mean depends on?

Answer 11

size of the sample and variability of data

Question 12

right skew?

Answer 12

typically the median is less than the mean

Question 13

if the data set is symmetric then?

Answer 13

the mean equals the median

Question 14

if the data set is skewed to the left then?

Answer 14

typically the mean is less than the median

Question 15

when do choose mode?

Answer 15

when calculating measure of center for the qualitative variable

Question 16

when to choose mean?

Answer 16

variable is quantitative with symmetric distribution

Question 17

when to choose median?

Answer 17

quantitative variable with skewed distribution

Question 18

range

Answer 18

the distance between the largest measurement and the smallest measurement in a data set

Question 19

sample standard deviation

Answer 19

formula is minusing each value with the sample mean and squaring that and then dividing that by n-1 and square root the whole thing

Question 20

s^2 symbol

Answer 20

sample variance

Question 21

sigma^2 symbol

Answer 21

population variance

Question 22

s symbol

Answer 22

sample standard deviation

Question 23

sigma symbol

Answer 23

population standard deviation

Question 24

formula for sample variance

Answer 24

same as standard deviation but without the square root

Question 25

what does the n-1 produce?

Answer 25

produces an unbiased estimator of population variance

Question 26

what does the empirical rule do?

Answer 26

relates the standard deviation to the proportion of the observed values of the variables in the data set that lie on an interval around the mean (mu)

Question 27

empirical guideline for symmetric bell shaped distribution

Answer 27

68% lie within 1 standard deviation of the mean; 95% lie within 2 standard deviations of the mean; 99.7% lie within 3 standard deviations of the mean

Question 28

steps for solving empirical rule questions

Answer 28

draw out a normal curve with a line down the middle and three to either side

write the values from your normal distribution at the bottom; start with the mean in the middle, then add standard deviations to get the values to the right and subtract standard deviations to get the values to the left

write the percent for each section (0.15, 2.35, 13.5, 34)

determine the section of the curve the question is asking for and shade it in

add up the percent in the sections that got shaded

Question 29

range/4 is equal to

Answer 29

s