chapter 3: descriptive statistics, numerical methods, and some predictive analytics

Question 1

what is the data set’s central tendency?

Answer 1

represents the center or middle of the data

Question 2

what is the population mean (μ)?

Answer 2

average of the population measurements

Question 3

Population parameter

Answer 3

number calculated from all the population measurements

describes some aspect of the population

population mean (μ (mew)) is part of this

Question 4

Sample statistic

Answer 4

number calculated using the sample measurements

describes some aspect of the sample

to find a point estimate of a population

Question 5

what is the sample mean

Answer 5

it is X bar

average of the sample

Question 6

what is the median

Answer 6

The value of the middle point of the ordered measurements

value such that 50% of all measurements lie above (or below) it

Question 7

what is the mode

Answer 7

The most frequent value

most frequently occurrent measurement in data

Question 8

what happens to the median if the number of measurements is odd

Answer 8

the median is the middlemost measurement in the ordering (In increasing order)

the most in the. middle

are the values that are observed “most typically”

Question 9

what happens to the median if the number of measurements is even

Answer 9

the median is the average of the two middlemost measurements in the ordering

Question 10

so what is the difference between the mean and the median

Answer 10

the mean will find the average

the median will find the most middle point of the measurements (in increasing order)

Question 11

what does it mean for data to have two modes

Answer 11

the data is bimodal

there is a higher frequency

Question 12

if there is skewness, should you use the mean or the median

Answer 12

median

If there is skewness, the mean is trash to use

Question 13

are all measures of central tendency necessarily typical values??

Answer 13

naaaah boyyy

Question 14

what is a point estimate

Answer 14

one number estimate of the value of the population parameter

should not be a blind guess

Question 15

what is “n” for the formula of the sample mean?

Answer 15

number of sample measurements

sample size

Question 16

will the sample mean always equal the population mean??

Answer 16

aaaah boy

unless you are extremely lucky

Question 17

what happens when more than two modes exist in data?

Answer 17

the data is multimodal

Question 18

what is a modal class?

Answer 18

only happens if data is presented in classes

it is the class having the highest frequency

Question 19

when is a mean or median used more than a mode?

Answer 19

when we want to describe a data set’s central tendency by using a single number

Question 20

why would we use the relative frequency curve on a histogram?

Answer 20

to smooth out the shape of the sample population

Question 21

describe the mean, median, and mode in a symmetrical relative frequency curve

Answer 21

the mean, median, and mode are all equal

Question 22

describe the mean, median, and mode in a skewed to the right relative frequency curve

Answer 22

mean > median > mode

mode is located under the highest point of the frequency curve

mean is larger cause it also average larger values

median is resistant to extreme values but mean is not

Question 23

describe the mean, median, and mode in a skewed to the left relative frequency curve

Answer 23

mean < median < mode

mode is located under the highest point of the frequency curve

mean is smaller cause it also average smaller values

Question 24

what is the range?

Answer 24

Largest minus the smallest
measure

Measures the interval spanned by all the data

Question 25

what is the variance

Answer 25

average of the squared deviations of all the population measurements from the population mean

Question 26

what is the standard deviation

Answer 26

The square root of the population variance

Tells you how much deviation there is between the population variance

Question 27

what are the there absolute measures

Answer 27

standard deviation

variance

range

Question 28

what is the empirical rule?

Answer 28

68. 26% of the population measurements
69. 44%
70. 73%

Question 29

when do we use the emperical rule?

Answer 29

When we have a symmetrical or bell shaped distribution, this shit works really well

If a population has mean µ and standard deviation σ and is described by a normal curve

Question 30

when is chebysev’s theorem practical?

Answer 30

With not much info, but do have mean of population (mew) and variance (sigma (sugma dicc))

Don’t use if its skewed af

Question 31

what is the chebysev’s theorem formula

Answer 31

100(1-1/k2)%