# STA215H5 Study Guide - Comprehensive Final Exam Guide - Standard Deviation, Variance, Normal Distribution

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Department

StatisticsCourse Code

STA215H5Professor

J.LeydonStudy Guide

FinalThis

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STA215 Lecture 1; Chapter 1

What is statistics?

● Collecting, analyzing, interpreting and presenting (visualization) of data

● Finding patterns and relationships within to draw conclusions

● Bigger picture: Take a sample and infer something about a larger population

● Examples;

○ Facebook is a social networking website where users can share pictures,

comments, links to news/websites, update friends/family on their

whereabouts, play games and chat live

○ Have you noticed Facebook also has ads that look very familiar or may be

related to things you viewed on other websites before?

■ This is because Facebook is collecting data based on your profile

through tools like Facebook Analytics and measurement tools

○ To Facebook, your data is a gold mine!! Your data can be sold to marketing

companies

○ Example: Facebook can sell your data to companies with their primary

consumers being university students and so your profile may be included

Data;

●Subjects or Participants are individuals on whom we experiment on

● Whereas Experimental units is typically reserved for animals, websites, and other

inanimate objects we conduct experiments on

● A population is the group of all items of interest. It is most often extremely large and

may, in fact, be infinitely large

● A sample is a set of data (subset) drawn from the studied population.

● A descriptive measure of a population is called a parameter or parameter of

interest.

● A descriptive measure of a sample is called a statistic.

●Statistical inference is the process of making an estimate, prediction, or decision

about a population based on sample data

Example;

● Suppose we want to find out the average distance UTM students live from campus.

Asking each and every UTM student would take forever. Instead, you decide to stand

at the bus stop and randomly ask 100 UTM students how far away they live. What is

the population, sample, parameter and statistic?

○ Population; UTM students

○ Sample; 100 UTM students

○ Parameter; average distance that entire utm students population live away

○ Statistic; average distance that the sample of 100 UTM students live away

Variables;

● A variable is some characteristic recorded about a population or sample. We usually

represent the name of a variable using uppercase letters (typically use X , Y, and Z)

● The values that the variable takes on are the possible observations of the variable

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○ Lowercase letters

● The data is the observed values of a variable

○ Actual numbers of entire variable we are interested in

● Focused on 3 types of variables;

○Categorical also known as qualitative or nominal variables, tell us which

group an observation belongs to. (Ex. male and female, left vs. right handed) -

nominal

○Quantitative variables contain numerical values with units of measurement.

(Ex. heights, weights, kilometres driven) - interval ratio

○Ordinal variables are variables that contain order without natural units. (Ex.

star ratings for a restaurant, rating your customer service experience) - ordinal

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