descriptive statistics

what are the categories in statistics

• descriptive

• inferential

descriptive statistics

used to summarize data

inferential statistics

techniques used to make generalizations about samples and apply them to populations

what are the types of variables

• discrete variable

• continuous variable

discrete variable

indivisible categories

continuous variable

infinite number of possible values

example of continuous variable:

• distance

• weight

• height

example of discrete variable:

number of cookies in a box

what are the types of scales

• nominal

• ordinal

• interval

• ratio

nominal

categorical data for which the order of categories is arbitrary

example of nominal scale:

major in college

ordinal

categorical data for which there is a logical ordering of the categories

order is preserved

example of ordinal scale:

military ranks

places in a race

birth order

interval

distance between numbers on scale are consistent although arbitrary

scale has ana arbitrary zero point

example of interval scale:

°C and °F

ratio

order is retained; intervals are consistent and the scale has an absolute zero point

example of ratio scale:

kelvin scale

distance

histograms

height of each bar represents how common each score is

numerical (quantitative)

bars touch each other

bar charts

data is discrete

categorical (qualitative)

bars are separated

purpose of bar chart:

compare different categories

example of bar chart:

comparing the popularity of different coffee flavors (Vanila, Mocha, Caramel, etc.)

purpose of histogram:

show the distribution of numerical data

example of histogram