types of data

data

pieces of information for analysis

quantitative variable

deals with numbers and amounts

quantitative variable

can be measured or support mathematical operations

qualitative variable

describe qualities or characteristics

qualitative variable

grouped into categories

levels of measurement

system that describes the nature of information within the values

nominal level

categorized without any

implied order or ranking.

ordinal level

ordered or ranked, not measurable

stanley smith stevens

developed the hierarchy of data that made them meaningful and mathematically permissible

interval level

measurable & meaningful differences between values, no true zero; zero has meaning

ratio level

absolute zero means none nothing

mean

sum of all values divided by the number of values.

mean

used when free from extreme values and computing average

median

middle value, average between 2 values

median

data are skewed

mode

Best used with categorical or nominal data

1. nominal

2. ordinal

3. interval

4. ratio

levels of measurement

1. mean

2. median

3. mode

measure of central tendency

measures of variablity

how spread out or the differences of the values in a data set

range

difference between the highest value and the lowest value in a data set.

range

simplest measure of variability

interquartile range

measures the spread of the middle 50% of the data.

variance

how far the observations are spread from the mean by finding the average of the squared deviations from the mean.

population variance

“All,” “entire,” or “every” group

sample variance

“Selected,” “random,” or “sample” from a larger group

standard deviation

typical distance of observations from their mean.