Stats quiz #2

Question 1

why do we present graphs

Answer 1

to present the distribution of the sample and track of observed values

Question 2

what is a dotplot

Answer 2

a graph where every observation is represented by a dot on a number line

Question 3

what are dotplots most useful for

Answer 3

small data sets

Question 4

what are stemplots uselful for

Answer 4

when theres no technology and data set isnt large

Question 5

what is a stemplot

Answer 5

it shows individual data values in a convenient way- leaf and stem

Question 6

what is the leaf vs stem

Answer 6

leaf is the last digit and all preceding digits are stem

Question 7

do you need units for leaeves

Answer 7

yes

Question 8

what is a histogram

Answer 8

observations put into bins which is a vertical bar the height being the frequency

Question 9

what are histograms good for

Answer 9

grouped data

Question 10

can you have an observation in mutlitple bins

Answer 10

no every observation has only 1 bin

Question 11

in a histogram, if the data is [3.5) is 5 included

Answer 11

no

Question 12

how do you find frequency

Answer 12

you add up all the values in the interval

Question 13

in a relative frequency histogram what does the heigh of bin represent

Answer 13

relative frequencyor

Question 14

for the relative frequency histogram what should be the summation of thr heigh of each bin

Answer 14

1

Question 15

in a density histogram what does the area of bin represent

Answer 15

relativr frequency

Question 16

on a density histogram what should be the total area of te bin

Answer 16

1

Question 17

how do you find relative frequency

Answer 17

you add all the vaues in an interval and divide it by the total frequency

Question 18

how do you find the density

Answer 18

you add up the values in an interval, divide by total frequency then divide by the number of numbers in interval or relative frequency/bin size

Question 19

what are the possible shapes of a graph?

Answer 19

symmestric or skewed (right skewed is tail to the right, left skewed is tail to the left)

Question 20

unimodal vs bimodal vs multimodal

Answer 20

1 mound, 2 mounds, 3+mounds

Question 21

what do bimodal and multimodal distrivutions mean

Answer 21

data from different groups

Question 22

what are outliers

Answer 22

extreme large/small values dont fit

Question 23

what is the center of a graph

Answer 23

the typical value

Question 24

difference btwn frequency and relative frequecny graph

Answer 24

relative will have a smaller y axis

Question 25

what is variability

Answer 25

the horizontal spread in a graph

Question 26

what is a bar chart

Answer 26

shows data categories on x axis, bar for height of frequency/relative frequency

Question 27

differences between bar and histogram

Answer 27

bar: categorical, bin width doesnt matter, no natural order histogram: numerical, bin width matters, values in numerical order

Question 28

what is a pie chart

Answer 28

a pie sliced into categories, area being the frequency

Question 29

in numerical distrubutions we look for what

Answer 29

shape, spread, center

Question 30

in categorical distributions we look for what

Answer 30

mode and variability

Question 31

what is mode

Answer 31

the category that occurs most often

Question 32

do the mounds need to be the same height for categorical or numerical data

Answer 32

categorical

Question 33

what is variabiliity

Answer 33

diversity in values

Question 34

what are misleading graphs

Answer 34

bar graphs- not starting y axis at 0 pie chart angles

Question 35

what are statistics

Answer 35

numerical property of a sample

Question 36

what is a parameter

Answer 36

numerical property of the population

Question 37

what is the sample mean

Answer 37

the measure of center/ balancing point shown by x with line over (x bar)

Question 38

how do you find the mean

Answer 38

you add up all the values then divide my number of values

Question 39

what is sample standard deviation

Answer 39

the measure of variability, shows if values are close or far from mean shown by s

Question 40

whats the formula for standard deviation

Answer 40

1. how far each value is from mean that distance is called the deviation 2. then square each deviation and add them up 3. divide by number of values-1 4. square root it

Question 41

what is the deviation

Answer 41

how far an observation is from mean

Question 42

what is the variance in relation to standard deviation

Answer 42

square root of variance = standard deviation shown by s^2

Question 43

what is the empirical rule

Answer 43

in a bell shaped distribution: - 68% of obsv are in 1 standard deviation - 95% of obsv are in 2 standard deviation - 99.7% of obsv are in 3 standard deviation

Question 44

what is a z score

Answer 44

it is how many standard deviations a value is from mean

Question 45

z score formula

Answer 45

how far the values are from mean divided by standard deviation

Question 46

what is wrong with using mean to find center

Answer 46

it does not account for modals

Question 47

ways to measure center and spread in skewed distribution:

Answer 47

median, quartiles, interquartile range, range

Question 48

what is the median

Answer 48

a measure of center in a skewed distrubution, cuts it in half, middle of ordered set

Question 49

median symbol

Answer 49

x with squiggly line over it called x tilde

Question 50

how do you find the median

Answer 50

1. sort data from small to large 2. find the middle or middle two values 3. if middle two then average them

Question 51

what are quartiles

Answer 51

the values that divide numbers into quarters

Question 52

what does the interquartile range show and the formula

Answer 52

how much space the middle 50% takes up, igr=q3-q1

Question 53

what is the range and the formula

Answer 53

the distance taken up my the data, max-min

Question 54

in a symmetric distribution what will the median and mean look like

Answer 54

they will be very similar

Question 55

in a right skewed distribution what will the median and mean look like

Answer 55

the mean will be greater than the median

Question 56

in a left skewed distribution what will the median and mean look like

Answer 56

median will be bigger than mean

Question 57

what is the best measure of center when theres outliers

Answer 57

median

Question 58

what is the best thing to do when the distribution of data has modals

Answer 58

split it into groups and measure each individually

Question 59

what is a boxplot

Answer 59

a tool to show distribution visually, using a box and min, q1, median, q3, max and shows outliers

Question 60

what is the lower fence

Answer 60

q1- 1.5xIQR = Q1-1.5X(Q3-Q1)

Question 61

When do outliers count on a boxplot

Answer 61

if they are below or above the lower or upper fence

Question 62

what is the upper fence

Answer 62

Q3+1.5XIQR= Q3 + 1.5 X (Q3-Q1)