Tabulating and Plotting Data

Question 1

what are two ways to summarize our numbers?

Answer 1

1. frequency distribution (table that shows classes-intervals of data with a count of the number of entries in each interval
2. graph (preferable because of pictorial representation)

Question 2

frequency

Answer 2

the number of data entries in that interval

Question 3

lower class limit

Answer 3

smaller number in interval

Question 4

how to find class width

Answer 4

if table given, subtract vertically

if only data given, (max#-min#/# of classes) and round to nearest integer

Question 5

how to find class limits from data given

Answer 5

lowest number=lowest limit, add class width to find lower limit of the next class/interval. Upper limit is just one less than the lower limit of the next class/interval.

Question 6

frequency histogram

Answer 6

bar graph that represents the frequency distribution

Question 7

x-axis=

Answer 7

quantitative data values

Question 8

y-axis=

Answer 8

frequency

Question 9

requirement of frequency histogram:

Answer 9

bars must be touching

Question 10

class boundaries

Answer 10

the numbers that separate classes on a frequency histogram, must be consecutive to allow for no gaps and touching bars)

Question 11

to find class boundaries:

Answer 11

+0.5 to upper limites and -0.5 for lower limits

Question 12

how to find midpoint of a class

Answer 12

(lower class limit + upper class limit)/2, this can be used to plot frequencies which changes label on x-axis but not the distribution

Question 13

positive skew

Answer 13

“trending” / stretching toward positive x-axis

Question 14

negative skew

Answer 14

“trending” / stretching toward negative x-axis

Question 15

frequency polygon

Answer 15

a line graph that emphasizes continuous changes in frequencies on midpoint lables

Question 16

how to construct frequency polygon from frequency distribution table?

Answer 16

line must start/end on x-axis, extend both ends by one class width past the first class midpoint

Question 17

what is a pro of using stem-and-leaf plots

Answer 17

still able to see original data values

Question 18

unimodal symmetrical

Answer 18

one mode or “peak,” has a centre of symmetry

Question 19

bimodal symmetrical

Answer 19

two modes or “peaks” of roughly equivalent height, has a centre of symmetry

Question 20

what is the number of peaks/distribution type based on?

Answer 20

the number of peaks observed on the graph, based on what it looks like. if the peaks are super close, in the same class or interval, it may look like one peak and thus be unimodal.

Question 21

negative skew is synonymous with:

Answer 21

left skew

Question 22

positive skew is synonymous with:

Answer 22

right skew

Question 23

kurtosis

Answer 23

extent of deviation from normal curve in width of curve and thickness of tails

Question 24

mesokurtic curve

Answer 24

“middle-ground” - this is the normal distribution

Question 25

leptokurtic curve

Answer 25

“tall and skinny” - tall and skinny peak, shortened tails

Question 26

platykurtic curve

Answer 26

“flat and wide” - lower peak and lengthened tails

Question 27

what is the goal of graphs?

Answer 27

to provide an accurate visual representation of your results

Question 28

what constitutes as cheating graphs that distort data?

Answer 28

truncated graphs without line break, no error bars (hard to confirm statistical significance), failing to adjust for distorting confounds (ex. correcting for population differences)