S1 - representation and summary of data - location Flashcards
quantitative variables
variables associated with numerical observations
qualitative variables
variables associated with non-numerical observations
continuous variable
a variable that can take any value in a given range
discrete variable
a variable that can take only specific values in a given range
cumulative frequency
the running total of the frequencies
grouped data
when data presented as a grouped frequency table, the specific data values are lost.
the groups are more commonly known as ______.
classes
you need to be able to find ___________, ___________ and ____________.
class boundaries, mid-point of a class and class width
measure of location/ average
a set of data can be summarized by giving a single number to describe its center.
there are three alternative measures of location
mode, the median and the mean
what is the mode
the mode is the value that occurs most often
what is the median
the median is the middle value when the data is put in order.
what is the mean
the sum of all the observations divides by the total number of observations
the mean of a sample of 25 observations is 6.4. the mean of a second sample of 30 observations is 7.2. calculate the mean of all
6.84
modal class
the class with the highest frequency
