Class notes
Class notes Chapter 4 STATS-2126 Essentials of Statistics for the Behavioral Sciences, ISBN: 9780357035580
- Course
- Statistics (STATS2126)
- Institution
- Laurentian University (LU )
lecture/chapter note (fall 2020)
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Seller
Follow
Content preview
1 of 13 Saturday, October 10, 2020Statistics Chapter 4 Notes
4-1 Introduction to Variability
Variability: Provides a quantitative measure of the differences between scores in a distribution
and describes the degree to which the scores are spread out or clustered together.
In general, a good measure of variability serves 2 purposes
1. Variability describes the distribution of scores. Specifically, whether the scores are
clustered close together or spread out over a large distance. Usually, variability is defined in
terms of distance. It tells how much distance is expected between one score and another,
or how much distance to expect between individual scores and the mean.
2. Measures how well an individual score (or group of scores) represents the entire
distribution. Important for inferential statistics, which are relatively small samples used to
answer questions about the population. When using a sample to represent a population,
variability provides information about how much error to expect between the sample data
and the population mean.
The Range
range = Xmax - Xmin
The distance covered by the scores in the distribution, from the smallest to largest score.
An alternative definition is often used when the scores are measurements of a continuous
variable.
range = URL (for Xmax) - LRL (for Xmin) URL => upper real limit
LRL => lower real limit
An alternative definition is used for discrete variables.
range = Xmax - Xmin + 1
Problem with range as a measure of variability is that it is completely determined by those 2
extreme values and ignores the other scores within the distribution.
- The range does’t consider all the scores in the distribution, therefore, it often doesn’t give an
accurate description of the variability for the entire distribution
• Range considered a crude and unreliable measure of variability.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller leahblain. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for CA$5.91. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
56326 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now