A sociologist studying freshmen carried out a survey, asking (among other questions) how often students went out per week, how many hours they studied per day, and how many hours they slept at night. The tables below provide the answers on the time slept and the time spent studying by whether or not students went out. 
When we examine the data, we find that students who studied more slept less, both among those who go out and among those who stay in the dorm. When we combine both groups of students, we find that those who studied more also slept more. This is an example of:
Definitions:
Collar
A protective options strategy that involves buying a put option and selling a call option on the same asset to limit the range of possible returns.
Putable Bond
A type of bond that allows the holder to sell the bond back to the issuer at a predetermined price before maturity.
Floating Rate
An interest rate that changes over time as it is tied to an underlying benchmark or index, commonly used in loans and bonds.
Bond Indenture
A legal contract between a bond issuer and bondholders, detailing the terms and conditions under which a bond is issued, including the interest rate, maturity date, and covenants.
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