Data AnalysisSpotlights - I
M.Elkharashy
Introduction
● Variables Types● Analysis Types● Random Samlping Vs Assignment● Exploring Numerical Variables
o Mesures of Centero Robust Statistics
● Exploring Categorical Variables
Variables Types
Quantitive/Numberical● Continuous ● Discreate
Qualitative/Categorical
● Regural● Ordinal
Notes:It can be represented by numbers, but without any arthimatic operations.Ordinal: variables that have ordered levels.
Variables Types
Dependent/Associated● +ve association ● -ve association
Independant
Analysis Types
Observational Study● Merely “Observe”● Retrospective/Prespective
use data (from past/ throughout the study)
● Can only establish an association between the explooanatory and response variables.
Experiment
● Randomly assign subjects to various treatments.
● Can establish causal connections between the explanatory and response variables.
Random Sampling
Random Assignment
ideal experiment
most experiments
most opeservational studies
bad observational studies
Exploring Numerical Variables
Dot PlotUseful when individual values are of
interest
Histogram
Box Plot
Useful for highlighting outliers, median, and the interquartile range.
Intensity MapUseful for highlighting the spacial distribution
Mesures of Center
Mesures of Center
Sample Statistics/Point Estimates● mean: arithmetic average ● median: midpoint of the distn. (50th
percentile)● mode: most frequent observation
Mesures of Center
Skewness Vs Mesures of Center
Robust Statistics
Robust Statistics
As a mesure on which extreme observation have little effect
Robust Statistics
As a mesure on which extreme observation have little effect
Exploring Categorical Variables
Exploring Categorical Variables
● Exploring single categorical variable.● Exploring the relationship between two
categorical variables● Exploring the relationship between a
numberical variable and categorical variable
1- Single Categorical VariableFrequency Table & Bar Plot
1- Single Categorical VariablePie Chart
Contingency Table
2- Relationship between 2 categorical variables
Segmented Bar Plot
2- Relationship between 2 categorical variables
Relative Freq. Segmented Bar Plot
2- Relationship between 2 categorical variables
Mosaicplot
2- Relationship between 2 categorical variables
Side-by-Side Box Plots
3- Rel. bet. numberical & categorical variables
● Disjoint events Vs independent process● Conditional probability & probability
trees● Normal distribution ● Binomial distribution● Centeral Limit Theorem (CLT)● Confidence Interval● Introductoin to Inference
In Next Session
● Another introduction to inference● Hypothesis testing(for mean)
o p-valueo test statistics (Z & T)o ANOVA
● Hypothesis testing(for proportion)o Chi-Square (GOF & Independence Test)
● Frequentist Vs Bayesian Inference● Linear Regression
In 3rd Session
Questions?
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