Due: Monday, October 28th at 11:59pm.

Late policy: You lose 20% of the grade for the project every day after the due date until you submit your project. Projects that are more than four days late will not be accepted.

Topics: variables, expressions, assignment statements, methods, conditional statements, using pre-defined classes, using objects.

Introduction

The bases of the estimate are the sale prices of the comps. Those prices, however, must be adjusted for several factors. For this project, you will consider the following factors:

• how long ago the comp sold, since home values generally increase over time;
• the age of the houses, since a newer house is generally worth more than an older house; and
• the size of the comp relative to the size of the subject ("size" means number of bedrooms, bathrooms, and square footage).

In more concrete terms, for each comp, your program should compute an estimated value using the following steps.

• Adjust the price of the comp for the time since its sale. If values have increased 5% since the sale of the house, you should add 5% to the sale price of the comp.
• Adjust the price of the comp for its age to get its value if it were brand new. To do this, we estimate that a house has a useful lifespan of 50 years. If a house is 10 years old, it has (50 - 10) / 50 = 80% of its useful life left. The estimate of its new price is then 125% of the value computed in the previous step (the reciprocal of 0.8 is 1.25).
• Adjust the price of the comp for the difference in size between it and the subject. Add (or subtract) $10000 for each extra bedroom the subject has (or lacks) when compared to the comp. Add or subtract $2500 for each full bathroom, and $1000 for each half bathroom. Finally, add or subtract to account for the difference in square footage. The amount to add or subtract for each square foot is how much it costs to build a ft² of living space from scratch and depends on the local market.
• The final estimate must take into account the age of the subject. If the subject is 25 years old, then the price should be halved (our formula gives a rather extreme adjustment, but things still work fairly well when comparing houses of similar age).

In even more concrete terms, consider a house in ZIP 18951 that was built in 1992 with 4 bedrooms, 2 full bathrooms, 0 half baths, and 2000 ft². Suppose there is one comp -- a house that sold for 100000 in 2000, was built in 1997, and has 3 bedrooms, 2 full bathrooms, 1 half bathroom, and 1800 ft² total.

We first adjust the price of the comp for how long ago it sold. Suppose that houses have gone up in value 10% since 2000. The adjusted price is then $110000. (This is the price the comp would fetch in 2002).

Next, adjust for the age of the comp. The comp is 5 years old, so has (50 - 5) / 50 = 90% of its life left. The new adjusted price is then $110000 / 90% = $122222. (This is the current value of a brand new 3 bedroom, 2-and-one-half bath, 1800 ft² house.)

Next, adjust for the size difference. First, add $10000 since the subject has one more bedroom than the comp. Then subtract $1000 since the subject has one fewer half bath than the comp. There is no adjustment for full bathrooms since the comp and the subject have the same number of full bathrooms. Assuming that the replacement cost is $25 per ft² in ZIP 18951 we add an addtional $25 * 200 = $5000 to account for the 200 ft² size difference between the two houses. The estimated price is now $136222. (This is the current value of a brand new 4 bedroom, 2 bath, 2000 ft² house.)

The final adjustment is for the age of the subject. It is 10 years old, so has (50 - 10) / 50 = 80% of its useful life left. 80% of $136222, or $108977, is our final estimate for the value of the subject.

For this project, you will examine one comp (extra credit: two comps) from the same ZIP code as the subject. Your final estimate will be the average of the estimates obtained from each comp.

You should also provide an estimate based solely on the cost of construction per ft², the age of the subject, and the value of a lot. (For example, we would estimate a 10 year old, 2000 ft² house in an area where construction costs $60 per ft² and lots cost $50000 to be $60 * 2000 * (50 - 10) / 50 + $50000 = $146000.)

Assignment

getValueByComps takes a HomeSaleDatabase as its parameter. It should ask that database to give it the most recent comparable sale in the same ZIP code as the subject. That comp is returned as a HomeSale object. Once it has the HomeSale object, it can ask that object about its attributes (size, age, etc.) and use those values to compute the value of the subject house according to the process described above. The attributes of the subject house will be available in the instance varaibles zip, numBedrooms, numFullBaths, numHalfBaths, size, and constructionYear.

getValueByCost should determine the size of the subject house (by accessing the appropriate instance variable) and the construction cost per square foot and lot value in the subject's ZIP code and should then use those three values to determine the replacement cost.

Both methods should return estimates that are rounded to the nearest $100.

Predefined Classes

HomeSaleDatabase

• HomeSaleDatabase(): a constructor used to initialize the database.
• int countComparableSales(int zip): given a ZIP code, this method returns the number of home sales in that ZIP code that are in the database.
• HomeSale getComparableSale(int zip): gets the data for the most recent home sale in the given ZIP code.
• HomeSale getComparableSale(int zip, int which): gets the data for a home sale in the given ZIP code. The second parameter determines which comp you get data for. Passing 1 gives you the most recent sale. Passing 2 gives you the next most recent sale, and so on.
• static double getAppreciation(int year): this method returns the percentage by which home values have risen since the given year (for 5%, it would return 5.0.
• static double getReplacementCost(int zip): returns the cost to build a new house per ft² in the given location.
• static double getLotValue(int zip): returns the cost of a lot in the given location.

• HomeSale(int, int, int, int, int, int, int, int): a constructor to initialize the object's data to the given values. In order, the eight ints are the ZIP code, number of bedrooms, full bathrooms, half bathrooms, square footage, year of construction, price, and year of sale.
• int getZIP(), int getPrice(), int getYearOfSale(), int getNumBedrooms(), int getNumFullBaths(), int getNumHalfBaths(), int getSquareFootage(), and int getYearBuilt(): getters for all of the data the HomeSale object holds.

Files

18036
4
2
1
2700
1996
268500
2000

18034
5
2
2
3400
1992
330000
2000

18036
4
2
1
3300
1997
312000
1999