Variables and Data in Descriptive Analytics

Categorical variables

qualitative variables

Nominal variables

cannot be ordered or ranked

Ordinal variables

can be ordered or ranked

Continuous variables

quantitative variables

Interval variable

zero doesn't mean an absence of value

Ratio variable

true zero exist

Descriptive statistics

speed up and simplify comprehension of a group's characteristics

Location

COLLECTION OF MEASUREMENT

central value of the variable

Variability

COLLECTION OF MEASUREMENT

the spread of the data from the center value

Central tendency

shows the center value in a dataset

- mean

- median

- mode

Mean

"average"

Mean

add up the values for each case and divide by the total number of cases

Mean

can be badly affected by outliers

Median

"middle value"

Median

the 50th percentile

Median

when data are listed in order, it is the point at w/c 50% of the cases are above & 50% below it

Median

unaffected by outliers

Mode

"most common"

Mode

possible to have more than one mode

Variation

summary of differences within group

- range

- interquartile

- variance

- standard deviation

Range

spread or the distance, between the lowest and highest values of a variable

Quartile

the value that marks one of the divisions that breaks a series of values into four equal parts

Quartile

25th percentile is a quartile that divides the first 1/4 of cases from the latter 1/4

Interquartile

the distance or range between the 25th percentile and the 75th percentile

Variance

measure of dispersion

Deviation

calculating variance starts with a _______________

Deviation

the distance away from the mean of a record's score

further

the larger the variance, the ________________ the individual cases are form the mean

closer

the smaller the variance, the ________________ the individual scores are form the mean

Standard deviation

the spread of the data in the original unit of measurement of the variable

Standard deviation

the square root of the variance reveals the average deviation of the observations from the mean