random sample

all members of the population are equally likely to be chosen

normal distribution

has data that vary randomly from the mean

percentiles

the value below which a percentage of data falls

measures of variation

describes how the data in a data set are spread out

sample

a part of a population

outlier

a number that is very far from the other numbers in the set

median

the middle number in an ordered set of numbers

standard deviation

measures showing how much data values deviate from the mean

margin of error

helps you find the interval in which the mean of the population is likely to be, it’s based on the size of the sample and the confidence level desired

conditional probability

the probability of an event B in relationship to an event A is the probability that even B occurs given that event A has already occurred

z score

the number of standard deviations that a value, x, is above or below the mean

binomial experiment

experiment that has a fixed number of trials, each trial is independent of the others, only two outcomes, and probability of each outcome remains constant from trial to trial

measures of central tendency

the mean, median, mode, and standard deviation of a set of data

standard normal curve

a “bell-shaped” curve for standard normal distribution

mean

the sum of the values in the set divided by the number of items in the set

range of a data set

the difference between the highest and lowest values in the set

mode

the value or values that occur most often in a set

confidence level

the percentage of all possible samples that can be expected to include the true population parameter