Class notes
Class notes Statistics 1: an introduction
- Course
- Institution
notes from the lectures
[Show more]
Seller
Follow
andrea1401
Content preview
Statistics 1Lecture 1
Measurement levels
A qualitative variable places each case into one of several groups (or categories)
o Label: no rank order, an identifier for each case
Participant/case number, name
o Nominal: no rank order
Hair colour, eye colour, bachelor programme
o Ordinal: rank order, distance between values is not the same
Socio economics status, 2nd person to enter lecture hall
A quantitative variable takes numerical values for which arithmetic operations, such
as adding and averaging make sense
o Interval: arbitrary zero, distance between values is the same, adding and
subtracting make sense
temperature
o Ratio: non-arbitrary zero, multiplication and division make sense
Weight, length, age
Rare in social sciences
Looking at data
Qualitative variables
o Graphical representations for categorical variables (nominal or ordinal)
Pie chart
Bar chart
Quantitative variables
o Graphical representations for qualitative variables
Stem and leaf plot
Histogram
Describing distributions with numbers
We can use a number to describe the “typical” score within a set of cases
Measures of central tendency
o Mean: add up all values and divide by the number of cases
o Median: the value in the middle (when values are sorted low to high)
o Mode: the value that occurs most frequently
Quartiles
o First quartile: value in the middle between the minimum and q2
o Median (q2): value un the middle
o Third quartile: value in the middle between q2 and the maximum
Five number summary
o Minimum, q3, median (q2), q3, maximum
o Accompanied by a box plot
, Distributions
Median
Mean
Variance
2
o s2= Σ(xi−x ̅ )
n−1
Standard deviation
√
2
o σ = Σ ( xi−μ )
N
Normal distributions
o Symmetric, single peaked, bell-shaped
Standard normal distributions
o μ=0
o σ =1
o N (0 ; 1)
o To standardize a value, we use Z-scores
x−μ
z=
σ
o 68, 95, 99.7 rule
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 andrea1401. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.68. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
48298 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 15 years now