STATS Exam 3

quantitative variable

numerical measurement in which operations such as addition and average make sense

quantitative is a

number

qualitative is a

quality(cannot be described by a number)

qualitative

describes an individual by putting into a category or group

population

all individuals of interest

parameter

numerical measurement that describes an aspect of a population

sample

subset of individuals of interest

statistic

numerical measure that describes an aspect of a sample

descriptive statistic

methods of organizing, picturing and summarizing information from samples or populations

inferential statistic

methods of using information from a sample to draw conclusions regarding the popoulation

simple random sample

every sample of size n, has an equal chance of being selected

random sampling

eliminates human bias

stratified sampling

divide the entire population into district subgroups

strata is based on

age, income, education level, and insures diversity

systematic sampling

number all members of a population using a sequence of numbers. then at a random starting point, include every k-th member in the sample

cluster sample

divide the entire population into pre-existing segments or clusters. The clusters are often geographic. Include every member of each selected cluster in the sample

cluster sampling pro

saves resources

systematic sampling pro

eliminates human bias

convenience sampling

use data from population members that are readily available

convenience sampling can…

save resources and be severly biased

class limits go from…

lower to upper

class boundary goes from…

lowest minus .5, and the upper plus .5

relative frequency is the…

frequency divided by the total number of observations

mean

sum of all data values divided by the number of data values

median

middle value

mode

the data value that occurs the most often

range

difference between the largest and smallest values

sample standard deviation

gives an average of a data spread around the mean (larger the SD, the more spread out the data is around the mean)

sample variance

square of a standard deviation, measure of data spead around the mean