ch 3/4 Flashcards
what are the steps in creating a frequency distribution table
- identify smallest and largest numbers, place the data in groups, count the number of observations in each group to find frequencies
what do histograms represent (x and y)
data and frequency
how do you find the relative frequency of a number
divide its frequency by the total number of observations
if putting numbers into a stem and leaf display, what would that look like (steps)
separate each number into stem (leading digit(s)) and leaf (SINGLE trailing digit)
put all the diff stems into a vertical column, and on the other side write the corresponding leafs
what characteristics describe a distribution curve for quantitative data
shape (unimodal, symmetric, outliers), centre, spread
how do you calculate mean
sum all the numbers up and then divide by the number of observations
how do you calculate median
either take the middle observation, or take the middle 2 observations and divide by 2
how do you calculate range
max. value- min. value
suspected outliers fall above or below
either Q1 -1.5x IQR or
Q3 + 1.5 x IQR
if distribution is roughly semetric.. use what as centre/spread measures
mean, variance, SD
if distribution is skewed, use what as centre/spread measures
median, IQR
what is the IQR
the range that falls in the middle 50% of observations