ISDS 2000 - Chapter 3

as a measure of central location what do you calculate?

Median

What is the symbol for population size?

N

What is a weakness of Mean as its used as the measure of central location?

it is unduly influenced by outliers

The average of the absolute differences between the values of the data set and the mean is the......

mean absolute deviation

What measures the difference between the largest and smallest values in a data set?

range

What is central location?

relates to the way data tends to cluster around some middle or central value

What is population mean?

represents the actual mean of the whole population (can't actually calculate this e.g. can't calculate average height of all men in USA)

the square root of the average of the sum of squared deviations from the mean is known as the......

standard deviation

When the observations are even and your trying to find the median it is most likely?

the average of the two middle observations

What is skewness?

the lack of symmetry of a distribution (the mean is usually greater than the median when the data are positive skewed and less when the data is negatively skewed.)

What is a median?

the middle value of the ordered observations in a sample or population. it goes in ascending order - useful when outliers are present

Using the weight mean formula what is the restrictions on the weights

the must sum to one

What are the two widely used measures of dispersion?

the variance and the standard deviation

bimodial is used when....

there are two modes

unimodal is used when.....

there is one mode

What are outliers?

very large or small numbers, numbers that don't fit the data stream

What is symmetry?

when one side is a mirror image of the other (the mean, median, and mode are equal)

What is weighted mean?

when some observations contribute more than others in the calculation of an average - calculate frequency distribution

What is the symbol for sample mean?

x̄

What is the symbol for the population mean?

μ

What is the symbol for the population variance

σ^2

The function to find the mean of a subset in excel is

AVERAGEIF

What is the primary measure of central location

Arithmetic mean

What is Arithmetic mean?

The average/mean between positive numbers- a+b/n - the primary measure of central location

What is sample mean?

This is the average of the sample taken. It is represented by the following equation:

What is the most frequently occurring observation in a sample or a population?

mode

what is the symbol for the sample size?

n