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