Sample Statistics - One Variable Flashcards
what does a measure of location tell us
typical or average values of the data
what does a measure of spread tell us
how widely spread the data is
what is sample mean
the sum of the numbers in the sample divided by the sample size
what is sample median
the middle value (or average of the middle values) when the observations are ranked in increasing order of magnitude
what can you say about the median and the cumulative relative frequency
at the median the cumulative relative frequency is around 0.5
how do you draw a cumulative polygon
join the top right hand corners of the rectangles of a histogram
what is sample mode
the value of the observation with the highest frequency
only defined for discrete variables
what is sample modal interval
the bin which has the greatest frequency of observations
multimodal data
several peaks in the line chart or histogram
what is the condition for data to be symmetric
if the sample mean is equal to the sample median
what is the condition for right skewed data
median<mean
what is the condition for left skewed data
median>mean
what is the ideal measure of location for roughly symmetric data
mean
what is the ideal measure of location for skewed data
median if we want to focus on the most typical observations
what is the sample variance
the mean squared distance to the mean
