Deck 2: Economists View of Behavior

Question 1

Define the following terms: marginal utility, ordinal utility, marginal rate of substitution, equal marginal principle, demand function, substitution effect, income effect, normal good, inferior good, perfect complement, and perfect substitute.

Answer 1

Utility is a concept associated closely with satisfaction where an attempt is made to measure it. Marginal utility is the additional or extra utility a consumer can receive when the consumption of a given good is increased by one more unit. Marginal utility is assumed as falling for each additional unit consumed.
Ordinal utility is the utility that cannot be measured and is considered subjective in nature. Due to this reason, consumption bundles can only be ranked so that the preferences can be investigated. Marginal rate of substitution is the slope of the indifference curve. It measures the rate at which the consumer is willing to substitute one good with the other.
The equal marginal principle argues that two goods should be consumed in such a way that marginal utility of each good divided by its price should be same for all the goods. This ensures that utility is maximized. Demand function shows a functional or mathematical relationship between quantity of a good demanded and factors influencing it.
A change in price of a good brings in income effect and substitution effect. The latter measures the change in the quantity of one good when its price changes, keeping the prices of other good and income of consumers unchanged. Income effect, in contrast, measures change in the quantity of one good when income changes, keeping the prices of all goods unchanged.
Normal goods are the ones that expect an increase in their demand when consumers have a higher income. Inferior goods are opposite in nature, in that they are demanded less when income of consumers is increased. Income effect is positive for normal goods while negative for inferior goods.
Two goods are called perfect complements when both of them are used together in a given proportion. Two goods are called perfect substitutes when consumers can readily switch between them so that maximization of total utility more important for them. Perfect complements have L-shaped indifference curves and perfect substitutes face downward sloping straight lines as indifference curves.

Question 2

Briefly describe the five models of behavior presented in this chapter.
b. What are the implications of these models for managers attempting to influence their employees' behavior

Answer 2

Models that attempt to predict the behaviour of individual economic agents are useful for managers. They are used to analyze the incentives economic agents face including consumers, employees as well as managers. Pricing decisions for consumers and compensation decision to employees are crucial for managers and these models come at their rescue.
a)
Economic model is one of the mostly used models that focus on rationality. Economic agents take decisions that maximize their own utility, suggesting that they take every decision in their self-interest. It involves a comparison of marginal benefit and marginal cost of an economic activity.
In contrast, product of the environment model argues for cultural and moral values affecting work ethics. Only money matters model and economic model argue that employees should be more productive if only monetary incentives matters. The happy is productive model suggests that employees are more productive when they are happy.
Under good citizen model, the basic assumption is that employees face a personal desire of being a good citizen by doing their job well. The feel proud of their work and want to excel in whatever they do. In that sense, they do not require any incentive pay since they are already motivated to do a good job.
b)
Managers can use any of these models depending on the circumstances at work and the workforce they have. Economic model is more useful to alter behaviour of consumers and employees. Good citizen model is not very useful in predicting behaviour in business settings.
Similarly, it is difficult for managers to keep employees always happy and so happy is productive model is less successful. Also, it is not necessary that the happier the employees are, the more productive they should be. Product of the environment is sometimes useful because it is easy to fire employees with undesirable traits.
However, most of these models have strong limitations and required only specific conditions for being successful. Hence, only economic model is most suitable in different circumstances for managers.

Question 3

Accounting problems at Enron ultimately led to the collapse of the large accounting firm Arthur Andersen. When the Enron scandal first became public, Andersen's top management blamed one "rouge partner" in the Houston office who they claimed was less honest than other partners at the firm. They fired the partner and asked that people not hold the remaining partners accountable for "one bad apple." What model of behavior was Andersen's management using when it analyzed the source of the problem According to the economic view of behavior, what was the more likely cause of the problem

Answer 3

Different models of economic behaviour have different explanations for the observed behaviour of employees at workplace. Under economic model, employees are expected to increase their productivity when their compensation is linked with their performance. In contrast, product of the environment model argues for cultural and moral values affecting work ethics.
In the given case, one partner firm was found relatively less honest than others. Company fired it in order to give an indication to its consumers that other partners should not be held accountable for one dishonest partner. This is consistent with product of the environment model because the dishonest partner did not possess the same moral values as possessed by other partners.
The management decides to replace the dishonest partner to with a new partner with higher moral and ethical values, who can work with more diligence. The economic behaviour of dishonest partner also reveals that there must have been incentives that guided its behaviour. The accounting firm must have an evaluation system that was favourable for breeding dishonesty.
This could be possible because there were incentives to obtain additional gains from auditing consumers by relaxing the audit process. This would be helpful in attracting additional consumers as well. Hence, the environment at work was made favourable for the less ethical partner.

Question 4

Which costs are pertinent to economic decision making Which costs are not relevant

Question 5

Employees in a plant in Minnesota are observed to be industrious and very productive. Employees in a similar plant in Southern California are observed to be lazy and unproductive. Discuss how alternative views of human behavior and motivation might suggest different explanations for this observed behavior.

Question 6

According to a recent article in The Atlanta Journal-Constitution ( January 29, 2004), "materialism, not necessity, gave birth to dual-income families." In supporting the argument, the author cites the following figures from the Department of Commerce: In 1970 the average wage per job was $6,900, which in 2001 dollars (adjusting for inflation) amounts to $31,500. In 2001, the average wage per job was $35,500. The main thesis of the article is that dual-income families are a result of a shift in consumer preferences toward consumption as opposed to leisure time/time spent with the family.
a. Assume the average person worked 250 days during a year both in 1970 and 2001, and that, as reported in the article, only one person worked in the average family in 1970, while both parents did in 2001. Provide a graphical analysis of the typical family's choice between family income and combined parent leisure time that supports the author's argument, relying on the tools presented in class. Be careful in labeling your graph(s), and provide a clear and concise explanation for your graph(s). Note that there are 365 days in a year so that the total parent leisure time that is possible is 730 days (assuming neither spouse works).
Assume it is possible for each family member to work anywhere from 0 to 365 days a year (at the going salary rate) if they choose to do so.
b. Assume that in 1971 the average single person worked 220 days per year, while the same person worked 260 days per year in 2001. Moreover, suppose the average daily wage in 2001 dollars was $125 in 1970 and $140 in 2001. Show graphically how the author's argument would not necessarily apply to the average single person (i.e., assume preferences are unchanged). Explain clearly and concisely why the average worker may be choosing to work more in 2001 and carefully label your graph.

Question 7

You own a business that services trucks. A customer would like to rent a truck from you for one week, while you service his truck. You must decide whether or not to do this.
You have an extra truck that you will not use for any other purpose during this week. This truck is leased for a full year from another company for $300/week plus $.50 for every mile driven. You also have paid an annual insurance premium, which costs $50/week to insure the truck. The truck has a full 100-gallon fuel tank.
The customer has offered you $600 to rent the truck for a week. This price includes the 100 gallons of fuel that is in the tank. It also includes up to 500 miles of driving. The customer will pay $.50 for each additional mile that he drives above the 500 miles. You anticipate that the customer will bring back the truck with an empty fuel tank and will have driven more than 500 miles. You sell fuel to truckers at a retail price of $4.00/gallon. Any fuel you sell or use can be replaced at a wholesale price of $3.25/gallon.
The customer will rent a truck from another company if you do not accept the proposed deal. In either case, you will service his truck. You know the customer and are confident that he will pay all charges incurred under the agreement.
Would your answer change if your fuel supplier limited the amount of fuel that you could purchase from him at the wholesale price Explain.

Question 8

Employees at a department store are observed engaging in the following behavior:
(a) they hide items that are on sale from the customers, and (b) they exert little effort in designing merchandise displays. They are also uncooperative with one another. What do you think might be causing this behavior, and what might you do to improve the situation

Question 9

You are a manager for a company that bottles and sells wine in two different countries. You charge the same price for a bottle of wine in both countries. Yet, your wine sales are much higher in one country than the other. Your boss asks you to develop an explanation for the differences in wine sales between the two countries and to develop a plan to sell more wine in the country with low wine consumption.
Population sizes and family incomes in the two countries are very similar. You also know that each country imposes a per bottle tax on wine.
Begin by providing a plausible economic explanation (focusing on constraints) for the differences in wine sales in the two countries. Illustrate your explanation by using indifference curves and budget lines for representative consumers from the two countries. What data would you want to determine if your explanation is likely to be correct Are there other plausible explanations for the differences in wine consumption Are there ways to determine which of these explanations is most likely to be driving the differences in consumption
Now provide a potential preference-based explanation for the differences in wine sales. Suppose that this explanation is correct. Discuss whether there are likely to be feasible policies that you could use to increase wine sales in the country with the low demand.

Question 10

One of the main tenets of economic analysis is that people act in their own self interest. Why then do people leave tips in restaurants If a study were to compare the size of tips earned by servers in restaurants on interstate highways with those in restaurants near residential neighborhoods, what would you expect to find Why

Question 11

Interwest Healthcare is a nonprofit organization that owns 10 hospitals located in three western states. Cynthia Manzoni is Interwest's chief executive officer. Vijay Singh, Interwest's chief financial officer, and the administrators of the 10 hospitals report to Manzoni.
Singh is deeply concerned because the hospital staffs are not being careful when entering data into the firm's management information system. This data involves information on patient intake, treatment, and release. The information system is used to compile management reports such as those relating to the costs of various treatments. Also, the system is used to compile reports that are required by the federal government under various grant programs. Singh reasons that without good information, the management and government reports are less useful and potentially misleading. Moreover, the federal government periodically audits Interwest and might discontinue aid if the reports are deemed inaccurate. Thus, Singh is worried about the managerial implications and the potential loss of federal funds.
Singh has convinced Manzoni that a problem exists. She also realizes the importance of an accurate system for both management planning and maintaining federal aid. Six months ago, she invited the hospital administrators and staff members from the corporate financial office to a retreat at a resort. The purpose was to communicate to the hospital administrators the problems with the data entry and to stress the importance of doing a better job. The meeting was acrimonious. The hospital people accused Singh of being a bureaucrat who did not care about patient services. Singh accused the hospital staffs of not understanding the importance of accurate reporting. By the end of the meeting, Manzoni thought that she had a commitment by the hospital administrators to increase the accuracy of data entry at their hospitals. However, six months later, Singh claims that the problem is as bad as ever.
Manzoni has hired you as a consultant to analyze the problem and to make recommendations that might improve the situation.
What information would you want to analyze

Question 12

Several school districts have attempted to increase teacher productivity by paying teachers based on the scores their students achieve on standardized tests (administered by outside testing agencies). The goal is to produce higher quality classroom instruction. Do you think that this type of compensation scheme will produce the desired outcome Explain.

Question 13

Susan Pettit's preferences for coffee (by the pound) and doughnuts (by the dozen) can be characterized as follows:

a. If the ratio of relative prices is ( P x / P y ) = 6/3 = 2, and Susan's income is $90 per period, what combination of pounds of coffee and dozens of doughnuts will she choose
b. Now let the ratio of coffee to doughnut prices decline to unity (=1), holding the price of doughnuts constant. How does Susan respond to the reduction in the relative price of coffee
c. Redo parts (a) and (b) for the case of income of $60 per period.
d. Derive Susan's demand function for coffee.
e. Is coffee a normal or inferior good for this consumer
f. Does Susan consider coffee and doughnuts to be either perfect complements or perfect substitutes Explain.

Question 14

A company recently raised the pay of employees by 20 percent. Employee productivity remained the same. The CEO of the company was quoted as saying, "it just goes to show that money does not motivate people." Provide a critical evaluation of this statement.

Question 15

A noted economist was asked what he did with his "free time." He responded by saying that "time is not free." Explain this response.

Question 16

One physician who worked for a large health maintenance organization was quoted as saying:
One day I was listening to a patient's heart and realized there was an abnormal rhythm. My first thought was that I hoped that I did not have to refer the patient to a specialist.
Indeed, HMO physicians have been criticized for not making referrals when they are warranted. How do you think the physician was compensated by the HMO Explain.

Question 17

Interwest Healthcare is a nonprofit organization that owns 10 hospitals located in three western states. Cynthia Manzoni is Interwest's chief executive officer. Vijay Singh, Interwest's chief financial officer, and the administrators of the 10 hospitals report to Manzoni.
Singh is deeply concerned because the hospital staffs are not being careful when entering data into the firm's management information system. This data involves information on patient intake, treatment, and release. The information system is used to compile management reports such as those relating to the costs of various treatments. Also, the system is used to compile reports that are required by the federal government under various grant programs. Singh reasons that without good information, the management and government reports are less useful and potentially misleading. Moreover, the federal government periodically audits Interwest and might discontinue aid if the reports are deemed inaccurate. Thus, Singh is worried about the managerial implications and the potential loss of federal funds.
Singh has convinced Manzoni that a problem exists. She also realizes the importance of an accurate system for both management planning and maintaining federal aid. Six months ago, she invited the hospital administrators and staff members from the corporate financial office to a retreat at a resort. The purpose was to communicate to the hospital administrators the problems with the data entry and to stress the importance of doing a better job. The meeting was acrimonious. The hospital people accused Singh of being a bureaucrat who did not care about patient services. Singh accused the hospital staffs of not understanding the importance of accurate reporting. By the end of the meeting, Manzoni thought that she had a commitment by the hospital administrators to increase the accuracy of data entry at their hospitals. However, six months later, Singh claims that the problem is as bad as ever.
Manzoni has hired you as a consultant to analyze the problem and to make recommendations that might improve the situation.
What actions might you recommend to increase the accuracy of the data entry

Question 18

Insurance companies have to generate enough revenue to cover their costs and make a normal profit - otherwise, they will go out of business. This implies that the premiums charged for insurance policies must be greater than the expected payouts to the policyholders. Why would a person ever buy insurance, knowing that the price is greater than the expected payout

Question 19

Susan's demand function for coffee in the previous problem includes only the price of coffee and income. Thus, changes in the price of doughnuts do not affect the demand for coffee. Does this imply that there is no substitution effect between the two goods Explain.

Question 20

Critically evaluate the following statement: "Risk-averse people never take gambles."

Question 21

The Solace Company has an inventory of steel that it originally purchased for $20,000. It currently has an offer to sell the steel for $30,000. Should Solace's management agree to sell Explain.

Question 22

Suppose that an investment can yield three possible cash flows: $5,000; $1,000; or $0. The probability of each outcome is 1/3.
a. What is the expected value and standard deviation of the investment
b. How much would a risk-neutral person be willing to pay for the investment
c. How much would a risk-averse person be willing to pay for the investment

Question 23

Interwest Healthcare is a nonprofit organization that owns 10 hospitals located in three western states. Cynthia Manzoni is Interwest's chief executive officer. Vijay Singh, Interwest's chief financial officer, and the administrators of the 10 hospitals report to Manzoni.
Singh is deeply concerned because the hospital staffs are not being careful when entering data into the firm's management information system. This data involves information on patient intake, treatment, and release. The information system is used to compile management reports such as those relating to the costs of various treatments. Also, the system is used to compile reports that are required by the federal government under various grant programs. Singh reasons that without good information, the management and government reports are less useful and potentially misleading. Moreover, the federal government periodically audits Interwest and might discontinue aid if the reports are deemed inaccurate. Thus, Singh is worried about the managerial implications and the potential loss of federal funds.
Singh has convinced Manzoni that a problem exists. She also realizes the importance of an accurate system for both management planning and maintaining federal aid. Six months ago, she invited the hospital administrators and staff members from the corporate financial office to a retreat at a resort. The purpose was to communicate to the hospital administrators the problems with the data entry and to stress the importance of doing a better job. The meeting was acrimonious. The hospital people accused Singh of being a bureaucrat who did not care about patient services. Singh accused the hospital staffs of not understanding the importance of accurate reporting. By the end of the meeting, Manzoni thought that she had a commitment by the hospital administrators to increase the accuracy of data entry at their hospitals. However, six months later, Singh claims that the problem is as bad as ever.
Manzoni has hired you as a consultant to analyze the problem and to make recommendations that might improve the situation.
How does your view of behavior affect how you might address this consulting assignment

Question 24

In order to spur consumer spending in 1998, the Japanese government considered an $85 billion voucher system whereby every Japanese consumer would receive a shopping voucher that could be used to purchase Japanese products. For simplicity, assume the following: Each consumer has wealth of 1 million yen, consumers must allocate this wealth between consumption now ( c 1) and consumption later ( c 2), the interest rate is zero, the voucher is worth 100,000 yen, and it can be spent only in the current period. If it is not spent, it is lost.
a. Plot a budget line for a representative consumer both before and after the voucher program ( c 1 and c 2 are on the axes).
b. Do you expect that current consumption of a typical consumer will increase by the full 100,000 yen of the voucher Explain.
c. How does the impact of this 100,000-yen voucher differ from simply giving the individual 100,000 yen

Question 25

(More challenging problem) Mario Casali is a TV newscaster who gets an annual clothing allowance to buy suits that he must wear during his televised forecasts. He allocates the allowance each year between expensive Italian suits and cheap American suits. Mario's utility function for suits is SA.5 where S is the number of Italian suits bought and A is the number of American suits bought. Last year, Mario bought two Italian suits and four American suits.
a. If Mario was maximizing his utility last year, what was the ratio of the price of an Italian suit to the price of an American suit ( P S / P A )
b. What was Mario's clothing allowance last year if the price of an Italian suit was $1,000
c. If Mario has the same allowance this year as last year, and American suit prices have not changed, how high would the price of Italian suits have to rise in order for Mario to want to buy exactly one Italian suit this year

Question 26

People give to charity.
a. Is this action consistent with the "economic view of behavior" Explain.
b. Suppose there is a big drop in charitable giving. At the same time there has been no decline in per capita income or total employment. Using the economic model, what potential factors might have led to this decline in giving
c. How might the decline in giving be explained by the product-of-the environment model

Question 27

You own a business that services trucks. A customer would like to rent a truck from you for one week, while you service his truck. You must decide whether or not to do this.
You have an extra truck that you will not use for any other purpose during this week. This truck is leased for a full year from another company for $300/week plus $.50 for every mile driven. You also have paid an annual insurance premium, which costs $50/week to insure the truck. The truck has a full 100-gallon fuel tank.
The customer has offered you $600 to rent the truck for a week. This price includes the 100 gallons of fuel that is in the tank. It also includes up to 500 miles of driving. The customer will pay $.50 for each additional mile that he drives above the 500 miles. You anticipate that the customer will bring back the truck with an empty fuel tank and will have driven more than 500 miles. You sell fuel to truckers at a retail price of $4.00/gallon. Any fuel you sell or use can be replaced at a wholesale price of $3.25/gallon.
The customer will rent a truck from another company if you do not accept the proposed deal. In either case, you will service his truck. You know the customer and are confident that he will pay all charges incurred under the agreement.
Should you accept or reject the proposed deal

Question 28

Suppose that you have $900 and what to invest the money for one year. There are three existing options.
(a) The city of Rochester is selling bonds at $90 per unit. The bonds pay $100 at the end of one year when they mature (no other cash flows).
(b) Put the money under your mattress.
(c) The one-year interest rate of saving in the Chase Bank is 7 percent.
Which one will you choose What is the opportunity cost of your choice Explain.

Question 29

The Japanese are very good at returning lost property to local police stations. If you lose a wallet filled with cash in Japan it is likely to be turned into the police. This is true even though the person finding it could keep it without anyone else knowing. This behavior is not what you would find in New York City.
a. Does this observation about Japan imply that the economic model does not explain behavior in Japan Explain.
b. Police stations in Japan are filled with lost umbrellas. It used to be that the typical Japanese would make a trip to the local police station to search for a lost umbrella. Now they don't. Explain this behavior using the Economic Model.
c. Do you think that the typical Japanese is more likely to come to a police station to find a lost cell phone or a lost umbrella Explain using the Economic Model.

Question 30

You are a manager for a company that bottles and sells wine in two different countries. You charge the same price for a bottle of wine in both countries. Yet, your wine sales are much higher in one country than the other. Your boss asks you to develop an explanation for the differences in wine sales between the two countries and to develop a plan to sell more wine in the country with low wine consumption.
Population sizes and family incomes in the two countries are very similar. You also know that each country imposes a per bottle tax on wine.
Begin by providing a plausible economic explanation (focusing on constraints) for the differences in wine sales in the two countries. Illustrate your explanation by using indifference curves and budget lines for representative consumers from the two countries. What data would you want to determine if your explanation is likely to be correct Are there other plausible explanations for the differences in wine consumption Are there ways to determine which of these explanations is most likely to be driving the differences in consumption
Suppose that your economic explanation is likely to be correct and that your company will not allow you to lower the price per liter that you charge for wine in the two countries. Discuss at least two potential actions that you might take to sell more wine in the country with low demand.

Question 31

Suppose Juan's utility function is given by U = FC , where F and C are the two goods available for purchase: food and clothing.

Question 32

Some states in the U.S. allow citizens to carry handguns. Citizens can protect themselves in the case of robberies by using these guns. Other states do not allow citizens to carry handguns. Criminals, however, tend to have handguns in all states. Use economic analysis to predict the effects of handgun laws on the behavior of the typical criminal. In particular: (1) Do you think criminals will commit more or fewer robberies in the states with the laws (2) How do you think the laws will affect the types of robberies criminals commit Be sure to explain your economic reasoning.

Question 33

Interwest Healthcare is a nonprofit organization that owns 10 hospitals located in three western states. Cynthia Manzoni is Interwest's chief executive officer. Vijay Singh, Interwest's chief financial officer, and the administrators of the 10 hospitals report to Manzoni.
Singh is deeply concerned because the hospital staffs are not being careful when entering data into the firm's management information system. This data involves information on patient intake, treatment, and release. The information system is used to compile management reports such as those relating to the costs of various treatments. Also, the system is used to compile reports that are required by the federal government under various grant programs. Singh reasons that without good information, the management and government reports are less useful and potentially misleading. Moreover, the federal government periodically audits Interwest and might discontinue aid if the reports are deemed inaccurate. Thus, Singh is worried about the managerial implications and the potential loss of federal funds.
Singh has convinced Manzoni that a problem exists. She also realizes the importance of an accurate system for both management planning and maintaining federal aid. Six months ago, she invited the hospital administrators and staff members from the corporate financial office to a retreat at a resort. The purpose was to communicate to the hospital administrators the problems with the data entry and to stress the importance of doing a better job. The meeting was acrimonious. The hospital people accused Singh of being a bureaucrat who did not care about patient services. Singh accused the hospital staffs of not understanding the importance of accurate reporting. By the end of the meeting, Manzoni thought that she had a commitment by the hospital administrators to increase the accuracy of data entry at their hospitals. However, six months later, Singh claims that the problem is as bad as ever.
Manzoni has hired you as a consultant to analyze the problem and to make recommendations that might improve the situation.
What are the potential sources of the problem

Question 34

Suppose that Bob's indifference curves are straight lines (as opposed to being convex to the origin). What does this imply about Bob's willingness to trade one good for the other Give examples of goods where this type of behavior might be expected

Question 35

Discuss the following statement: "Sunk costs matter. People who pay $20,000 to join a golf club play golf more frequently than people who play on public golf courses."

Question 36

Lauren Arbittier decides to bet $2,000 on number 35 of the roulette wheel in a Las Vegas casino. Almost immediately she starts to question her decision. Lauren normally is a risk avoider who hardly ever gambles. But she works at Trilogy Software where the CEO understands that taking risks and suffering the consequences are critical to the firm's success. The CEO wants to develop people who take chances. "You don't win points … for trying." Lauren is participating in Trilogy's three-month training program for all new recruits. It educates employees about, among other things, how to evaluate risky projects, not just to immediately accept or reject the project because it is risky. The program also suggests to employees that they will not be rewarded at Trilogy unless they take risks. Thus, although Lauren does not like taking risks, working for Trilogy, she has economic incentives to do so.
There are at least three ways in which the Trilogy training program might be effective: (1) It changes employees' preferences regarding risk bearing. (2) It more effectively identifies individuals with the risk to tolerances that Trilogy desires. (3) It better communicates the consequences to Trilogy employees of undertaking risky ventures. Discuss the likely importance of these three mechanisms.
SOURCE: E. Ramstad (1998), "High Rollers, How Trilogy Software Trains Its Raw Recruits to Be Risk Takers," The Wall Street Journal (September 21), A1.

Question 37

Suppose that Bob's indifference curves are perfectly L-shaped with the right angle occurring when Bob has equal amounts of both goods. What does this imply about Bob's willingness to trade one good for the other Give examples of goods where this type of behavior might be expected

Question 38

Jenny is an investor in the stock market. She cares about both the expected value and standard deviation of her investment. Currently she is invested in a security that has an expected value of $15,000 and a standard deviation of $5,000. This places her on an indifference curve with the following formula: Expected Value = $10,000 + Standard Deviation.
a. Is Jenny risk averse Explain.
b. What is Jenny's "certainty equivalent" for her current investment What does this mean
c. What is the risk premium on her current investment