Summary of all lectures supplemented with the material from the book. Various examples were also included for clarification.
Summary of all lectures supplemented with the material from the book. Also included several examples for clarification.
Up to 8 for my exam;).
Test Bank For Applied Statistics I Basic Bivariate Techniques 3rd Edition by Rebecca Warner All 1-18 Chapters Covered ,Latest Edition, ISBN:9781506352800
Test Bank For Applied Statistics I Basic Bivariate Techniques 3rd Edition by Rebecca Warner, ISBN: 9781506352800, All 18 Chapters Covered, Verified Latest Edition
Methods, Measurement & Statistics
All for this textbook (5)
Written for
Tilburg University (UVT)
Human Resource Studies
(424025B6)
Seller
Follow
nele_van_beek
Reviews received
Content preview
SUMMARY STATISTICS
LECTURE 1 INTRODUCTION TO STATISTICS
Statistics:
Descriptive statistics: describe/summarize data
o Reduce the data to understandable pieces of information
o Example; what proportion of Dutch adults has a driver’s license?
o Example; what is the average delay across all train travels?
Inferential statistics: drawing inferences about populations
o Draw conclusions about populations
o Example: Are COVID-19 vaccines safe and effective in the general
population?
o Problem: we can often only make observations on a selection of cases from
a population
o Solution: inferential statistics to find out if the sample results can be
generalized to the population.
Statistical modelling: studying complex multivariate relationships
o Interested in relationships between several variables
o People differ in their scores on those variables.
o Example: to what extent does years of education predict healthy lifestyle,
controlled for income?
MEASUREMENT LEVELS
Quantitative variables: provide information about the amount of something (e.g.
height or blood pressure for each person)
Different measurement levels:
Which you can describe in words:
Categorical variables: identify group (or category) membership (e.g. male or female)
1. Nominal variables: is the same as categorical variables because serve only
names or labels for groups. It has no order, like the Netherlands, Germany, Spain
or married/divorced.
o Must be exhaustive (all possibilities are covered) and mutually exclusive
(every case fits into one category and only one)
2. Ordinal variables: knows an order, such as age: 21, 22, 23 or I don't think
anything is stupid, neutral or fun.
Example: (1=never, 2=at least 1 cigarette per month, but less than 1 per
day, 3=at least 1, but less than 5, 4= 5 or more)
Scale variable: expressed in numbers
3. Interval: is if 0 means something NO TRUE ZERO POINT
o For example it is 0 degrees Celsius = the temperature that water freezes
(so is something)
o Also IQ score
4. Ratio: is if 0 means nothing
o For example I walk 0 meters to the right = walks nothing to the right
o Length, weight or income
Both interval-level and ratio-level data are referred to as scale data: all variables are not
nominal or ordinal so they are treated as scale-level variables.
Measurement Different Ordering Differences Natural zero
level categories expressed in point
common unit
Nominal Yes
Ordinal Yes Yes
, Interval Yes Yes Yes
Ratio Yes Yes Yes Yes
Measurement levels determine the kind of statistics and statistical analyses you can
use meaningfully.
Data inspection
Every analysis starts with data inspection (getting to know your data): to make sure
you will get a clear picture of the data examining one variable at the time (univariate) or
pairs of variables (bivariate).
In general, we want to know more about:
1. Central tendency: what are the most common values?
2. Variability: how large are the differences between the subjects? Are there
extreme values in the sample?
3. Bivariate association: for each pair of variables, do they associate/covary (i.e.,
do low/large values on one variable go together with low/large values on the
other variable?)
To get a clear picture of the data, we use:
Visual data inspection (graphs)
Numerical data inspection
(statistics)
which we use depends on the measurement levels
Visual data inspection
Bar charts (nominal & ordinal)
Histograms (scale)
Scatterplots (scale + 2 variables)
Figure 2 Histogram
Figure 3 Bar Chart
Figure 1 Scatterplot
The normal distribution (Gauss curve)
Symmetrical distribution
Useful statistical properties
o Examples: IQ score, length, birthweight
NUMMERICAL DATA INSPECTION
Numerical data inspection: three common statistical approaches
Frequency tables: counts & percentages
o Nominal & ordinal data
, Central tendencies: what is the centre of scores on a variable?
o Nominal, ordinal & scale data
Variability measures: how much variation is there in variable scores?
o Ordinal & scale data
, Frequency table (1 variable)
Crosstable (2 variables)
Central tendencies
Mode: the score that is observed most frequently
For nominal, ordinal or scale data
Example:
(3, 4, 4, 5, 5, 5) => mode is 5
Median: the score that separates the higher half of data from the lower half
For ordinal or scale data that are not normally distributed
Example 1: (N = unequal): 5, 6, 7, 8, 9 => median is 7
Example 2: (N = equal): 5, 6, 8, 9 => median is 7
Mean (M): sum of all scores (∑ is the summation sign) / total number of scores
For ordinal or scale data that are normally distributed
Frequency close to 50% (cumulative percentage)
Example: 2, 3, 20 => mean is 15/3 = 5
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 nele_van_beek. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.04. You're not tied to anything after your purchase.
