Basic Descriptive Data Analysis

Question 1

frequency distribution table

Answer 1

ranked order scores that shows the number of times each value occurred

Question 2

categorical data contains what in a frequency distribution table

Answer 2

raw and relative frequency

Question 3

continuous data contains what in a frequency distribution table

Answer 3

raw, relative, cumulative

Question 4

raw frequency

Answer 4

how many fall into that data, usually whole number

example: 5/27 people were age 0-10

Question 5

relative frequency

Answer 5

how does the number of data points relate to the entire sample, in %

example: 5/27 = 18.5 %

Question 6

cumulative frequency

Answer 6

cumulative % up to indicated range you are looking at

Question 7

class intervals (BIN)

Answer 7

defined range limits in which data is grouped

Question 8

categorical variables

Answer 8

separate due to lack of relationship to one another - ranking order tho

Question 9

what are two major statistical outputs of categorical data

Answer 9

frequency and percentage

Question 10

what constitutes a normal distribution curve

Answer 10

bell shaped curve

symmetrical around the mean

Question 11

what is the statistical significance of normal distribution?

Answer 11

many datasets follow the bell shaped symmetrical around the mean shape

Question 12

what does bimodal mean

Answer 12

bad, “two humps”

suggestive of 2 different populations

Question 13

left skewed

Answer 13

negatively skewed

tail is to the left

Question 14

right skewed

Answer 14

positively skewed

tail is to the right

Question 15

stem and leaf plot

Answer 15

used with continuous data

good for showing individual data
bad for large amounts of data

Question 16

histogram

Answer 16

continuous data

we can get distribution curves with a histogram
good for showing midpoint of data and large amounts of data
bad for showing individual data

Question 17

mean

Answer 17

equals sum of all values / total number of values

Question 18

when is mean commonly used

Answer 18

used for measuring central tendency

Question 19

when is mean less helpful

Answer 19

when outliers present or with skewed distribution

Question 20

median

Answer 20

equals value of middle of ranked data

Question 21

when is median most helpful

Answer 21

more helpful than mean when outliers present or with skewed distribution

Question 22

mode

Answer 22

equals value that occurs most often

less commonly used compared to mean and median

Question 23

what is the relationship between mean, median and mode with symmetrical data

Answer 23

mean = median = mode

Question 24

what is the relationship between mean, median and mode with right skewed data

Answer 24

mode < median

Question 25

what is the relationship between mean, median and mode with left skewed data

Answer 25

mode > median

Question 26

range

Answer 26

nominal and ordinal

2 extreme scores
can be listed as interval, misleading value is outliers present

Question 27

percentiles

Answer 27

describes a scores position within distribution

Question 28

interquartile range

Answer 28

Q3 - Q1

more helpful than range when outliers present

Question 29

Q1

Answer 29

value that occurs at the first quarter mark (25%)

Question 30

Q2

Answer 30

value that occurs at the second quarter mark = median

Question 31

Q3

Answer 31

value that occurs at the third quarter mark (75%)

Question 32

box plot

Answer 32

summary in 5 numbers

min, Q1, Q2/median, Q3, max

Question 33

pros and cons of box plots

Answer 33

large number set

do not keep exact values
lose info within data

Question 34

standard deviation

Answer 34

average absolute distance of each point from the mean

Question 35

what is standard deviation helpful for

Answer 35

distinguishing statistically significant data points from random fluctuations

Question 36

proportional area under a normal curve: 68 %

Answer 36

within 1 standard deviation from the mean

Question 37

proportional area under a normal curve: 95 %

Answer 37

within 2 standard deviation from the mean

Question 38

proportional area under a normal curve: 99.7 %

Answer 38

within 3 standard deviations from the mean

Question 39

coefficient of variation

Answer 39

unitless measures that depicts the size of the SD relative to the mean

especially helpful when comparing variation of greater than or equal to 2 variables measured in different units

often expressed as a %