Stat 101 Chapter 3

Uniform

distribution in which all outcomes are equally likely

Bimodal

distribution is a continuous probability distribution with two different modes

Multimodal

distribution with more than one peak or mode

Unimodal

distribution with one clear peak or most frequent value

Median

the value with exactly half the data values below it and half above it

Interquartile Range

IQR measures the variability of the center 50% of the data values (IQR = Q3 - Q1)

5-number Summary

Summarizes the distribution of our data using five values we have seen so far (minimum, Q1, median, Q3, maximum)

Skewed (right/left)

a measure of the asymmetry of the probability distribution of a real-valued random variable about its mean

Sample Mean

an estimate of the population mean

Histogram

answer questions about how the variable is distributed, picture of the distribution for one quantitative variable

Q1 and Q3

Q1 the 25th percentile or the median of the data values in the lower half of a data set Q3 the 75th percentile or the median of the data values in the upper half of a data set

Quantitative Variable

Variables with numbers as values

Outliers

lie away from the body of the distribution

Sample Variance

the average of the squared differences from the mean

Range

the difference between the largest and smallest values

Percentile

the kth percentile is the value that k% of the data is below (smaller)

Mode

the number with the highest occurrences in a set of data

Shape

use graphics to understand the shape of a distribution (histogram, stem and leaf, boxplot)

Variability

use summary statistics to understand how spread out a distribution is (range, IQR, standard deviation, percentiles, quartiles, five number summary)

Center

use summary statistics to understand where the center of a distribution is located (median, mean)

Sample Standard Deviation

used as a measure of the dispersion or variation in a distribution, equal to the square root of the arithmetic mean

Stem and Leaf Display

used for smaller data sets, picture of the distribution for one quantitative variable

Minimum and Maximum

values of the largest and smallest

Symmetric

values of variables occur at regular frequencies, the mean median and mode occur at the same point