STAT 2507 Study Guide - Fall 2018, Comprehensive Midterm Notes - Statistical Unit, Academic Grading In The United States, Variance
12 Oct 2018
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STAT 2507
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Stats- chapter 1
Descriptive statistics: science of summarizing and describing the important characteristics of a
set of data
Inferential Statistics: science of using information obtained from a sample to infer about the
characteristics of a population of interest
Population: set of entire collection of units
Sample: subset of the population selected in some prescribed manner
Variable: characteristic that changes or varies over times or for different individuals or objects
under consideration
Experimental unit: individual or object on which a variable is measured. Single measurement
or data value is obtained when a variable is actually measured on an experimental unit
Exercise 1
Population: all undergrad students at this university
Sample: five students
Experimental unit: a student
Measurements: GPA, Gender, Major, Credits
Types of data
➔ Univariate data: obtained when a single variable is measured on a single experimental
unit
➔ Bivariate data: obtained when two variables of measured on a single experimental unit
➔ Multivariable data: obtained when more than two variables are measured
Types of variables: qualitative or quantitative
➔ Qualitative (Categorical):
o measure a quality or characteristic on each experimental unit
o measurements of qualitative variables belong to one of several categories
▪ examples:
• Political affiliation: Liberals, Conservatives, NDP, Green,
Independent
• Colour of a car
• Size of t-shirts: XS, S, M, L, XL
• Racers classified as coming in 1st, 2nd, 3rd, etc
find more resources at oneclass.com
find more resources at oneclass.com
➔ Quantitative Variables
o Measure a numerical quantity or amount on each experiment unit
▪ Examples:
• x= Prime interest rate
• x=A person’s weight
• x=volume of orange juice in a glass
• x= the amount of rain in a specific day in Ottawa
*** Quantitative variables can assume either continuous or discrete values***
➔ discrete: assume only a finite or countable number of values; x=0,1,2,3..
➔ Continuous: assume the infinitely many values corresponding to the points on a line
interval; 0<x<5
Exercise 2 (qualitative or quantitative)
1) Qualitative
2) Quantitative; discrete
3) Qualitative
4) Quantitative; continuous (time never stops)
5) Quantitative; discrete
Exercise 3 (discrete or continuous)
1) Continuous (averages are always continuous)
2) Discrete
3) Continuous
4) Discrete
5) Continuous (volume is always continuous)
Graphs for qualitative data
➔ Best way to present data is either bar chart or pie chart
o Frequency or number of measurements in each category
o Relative frequency or proportion of measurements in each category
o Percentage of measurements in each category
▪ Example:
• A 50 (frequency) 50/100(relative frequency) 0.5(percent)
• B 20 20/100 0.2
• C 30 30/100 0.3
o Bar chart: shows distribution of measurements in categories, height of the bar
measuring how often a category was observed
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Descriptive statistics: science of summarizing and describing the important characteristics of a set of data. Inferential statistics: science of using information obtained from a sample to infer about the characteristics of a population of interest. Sample: subset of the population selected in some prescribed manner. Variable: characteristic that changes or varies over times or for different individuals or objects under consideration. Experimental unit: individual or object on which a variable is measured. Single measurement or data value is obtained when a variable is actually measured on an experimental unit. Univariate data: obtained when a single variable is measured on a single experimental unit. Bivariate data: obtained when two variables of measured on a single experimental unit. Multivariable data: obtained when more than two variables are measured. Qualitative (categorical): measure a quality or characteristic on each experimental unit, measurements of qualitative variables belong to one of several categories, examples, political affiliation: liberals, conservatives, ndp, green,
