Notes, summaries, assignments, exams, and problems for Mathematics

Distribution of Moody's Ratings

Historical Default Rates

• Rating Agencies
• Default rates from bonds
• Market Data

CAPM Model for Bond Returns

The usual CAPM has to be modified to include expected loss per year.

What must the β be to justify the excess spread for Baa Bonds?

Merton's Model

A Structural Model That Predicts Default Rates

How Do We Find V₀ and σ_V?

We know E₀ and σ_E, and

An application of Ito's lemma shows

These allow us to find V₀ and σ_V from E₀ and σ_E.

Default Correlation

Defaults: If Firm A Defaults, is Firm B More Likely to Default Too?

No Default Correlation

Consider two firms, X and Y:

Q_X = 0.1, Q_Y = 0.2

If X and Y are uncorrelated, then the probability that they both default is Q_X × Q_Y = 0.02

Building Default Correlation

If X and Y are correlated,... Continue reading "Understanding Bond Default Rates and Correlation" »

Final Exam Cheat Sheet

Machine Rate Problems

Chapter 1: Categorical (Qualitative) Data

What is Categorical Data?

Categorical data describes the qualities of individuals or objects, rather than quantities. It's about characteristics that can be grouped into categories.

Examples of Categorical Data:

• Hair Color
• Preferred Clothing Brand
• Nationality

Visualizing Categorical Data:

Categorical data is often displayed using:

• Bar Charts
• Pie Charts
• Tables

Chapter 2: Quantitative Data

What is Quantitative Data?

Quantitative data deals with numbers and measurements. It allows for comparisons and mathematical operations.

Examples of Quantitative Data:

• Height
• Weight
• Age

Visualizing Quantitative Data:

Quantitative data is often presented using:

• Dot Plots
• Stem Plots
• Histograms

Measures of Center

• Mode: The most frequent value

Bond Price Sensitivity

7.7 Interest rate sensitivity. An investor purchased the following 5 bonds. Each bond had a par value of $1,000 and an 8% yield to maturity on the purchase date. Immediately after the investor purchased them, interest rates fell, and each of them had a new YTM of 7%. What is the percentage change in price for each bond after the decline in interest rates? Fill in the following table:

N=10 Y=8 or 7 PV=? FV=1000 PTM=0 except coupon=100

Default Risk Premium

6.4 Default risk premium. A treasury bond that... Continue reading "Bond Price Sensitivity and Default Risk Premium Analysis" »

Vocabulary

English Definitions

Leading questions: Questions that encourage someone to answer in a certain way.

Mutually exclusive: Not able to be true or correct at the same time.

Weight: To give something more importance than something else.

Incentive: Something that will encourage people to do something.

Respondent: Person who completes a survey.

Analyse: To examine closely.

Ambiguity: When something has more than one possible meaning.

Jargon: Words used by one group of people, that other people might not understand.

Feedback: Opinions about something.

Dropout rate: The percentage of people who stop the survey before they have completed it.

Spanish Definitions

Liderar preguntas: Preguntas que animan a alguien a responder de cierta manera.

Mutuamente excluyentes:

Statistical Moments

A moment is a specific quantitative measure that characterizes a distribution. Two distributions are equal if their moments are equal.

Types of Moments:

• Related to the origin (0 as a reference)
• Related to the mean (μ as a reference)

M_r = (Σ(X_i – O)^r.n_i)/N

Where:

• X: individual observations
• r: Order of the moment (Order zero: r=0, First order: r=1, Second order: r=2, Third order: r=3)
• O: Origin or reference point
• n: frequency of each observation
• N: total number of observations

Properties:

• All moments of r=0 are equal to 1.
• Moments related to the mean are frequently called central moments.
• Moments with reference point 0 are frequently called ordinary moments.
• The arithmetic mean corresponds to the ordinary moment of the first order (r=

) Hypotheses, Type I and Type II Errors, and Statistical Tests

For each of the following tests, state the hypotheses, identify if it is a right-, left-, or two-tailed test and write Type I Error and Type II Error pertaining to the problem.

1. a) A professor of statistics states that the average student spends 3 hours studying for the midterm exam. Ho: μ = 3 vs. Ha: μ ≠ 3 Two-tailed test Type I Error: Concluding the average student doesn’t study 3 hours for midterm when in fact that is false. Type II Error: Not concluding the average student doesn’t study 3 hours for midterm when in fact that is true.
2. b) A spouse stated that the average amount of money spent on Christmas gifts for immediate family members is above $1,200. Ho: μ = 1200 (or

Linear Programming

Linear Programming is an optimization technique useful for allocating scarce resources among competing demands.

Examples of LP Applications

• Selecting the product mix in a factory to make the best use of machine and labor hours available while maximizing the firm’s profit.
• Scheduling tellers at banks so that needs are met during each hour of the day while minimizing the total cost of labor.
• Determining food ingredient combinations that satisfy stated nutritional requirements at a minimum cost level.

Basic Concepts

• A single objective function states mathematically what is being maximized or minimized.
• Decision variables represent choices that the decision maker can control.
• Constraints are limitations that restrict the decision variables.

Golden circle:

This relates to the innovation. If a company is able to attract those who share its beliefs, it is also able to connect easier with innovators.

This is a graph made up of three circles, each inside the other. Each circle has a meaning and a way to apply it to our business efficiently.

We can explain the operation of the Golden Circle in such a way that while most companies ask themselves the answers to the question 'what' as their starting point, they are fully aware of the 'how', but very few companies are clear about the 'why'.

The 'what' responds to what we do and what we want to do. The 'how' responds to the processes through which we carry out our actions, and the 'why' would respond to the reason why we develop our business.... Continue reading "The Golden Circle: Driving Innovation and Quality Management" »