Mean and Median
What is the median
The median is the number in a data set, when the data set is organized from most to least, that divides that data set. If the data set is composed of an odd number of values, the median is a single, unique value. If the data set is composed of an even number of values, the data set is the average of the two middle values.
what is the weighted mean
A mean in which the relative frequency of data values is reflected
How do you find mean for raw data
Arrange data from smallest to largest and determine the number of values. If the median is the average of two numbers, these are the n/2th number in the data set and the n/2th number+1. If the median is a single number it will be the n+1/2th number
How do you calculate weighted mean for grouped data
For grouped data, you use a formula involving the midpoint, which stands in for its class. First, calculate the midpoint for each class. Then, multiply the midpoints by the frequency of their classes, add them, and divide by the total number of observations in all classes. Essentially, you are calculating the mean using the midpoints as standings for the classes.
Is the mean a typical value?
N O
how do you find the mean for ungrouped data
Order the values from most to least. Generate their cumulative frequencies. calculate the median from the total frequency, using the formulas you know. The first value which has a cumulative frequency equal to or greater than the median, or medians is the one you want. It is possible, if you are working with an even total frequency number, that the n/2th value and the n/2+1th value will be different.
How do you calculate weighted mean for ungrouped data in a table
The sum of the products of each data value times its frequency divided by the total number of data values. Alternatively, the sum of each frequency value divided by the total number of data values, and multiplied by its corresponding data value. This could also be stated as multiplying each data value by its relative frequency and summing the products.
How do you find the mean of raw data
sum all the data values and divide by the number of data values
how do you find the median for grouped data?
the same method as finding the category to which the median belongs is used to find the class to which it belongs. This hideous formula is then applied. the Median is equal to: The total number of observations multiplied by two, minus the cumulative frequency of the class that precedes the median class, divided by the FREQUENCY OF THE MEDIAN CLASS and then multiplied by class width. All of this is added to the lower boundary limit of the median class.
