BE01106 – BUSINESS STATISTICS

Task  : 

The Assignment Data (PopulationPropertyData.xls) file, which you can access from the Assessment Information page on the unit website contains, in the range A1:I401, real estate sales data for a population of 400 properties around Melbourne in a particular week.

You are required to select a random sample of 50 properties from this population. The variables in the data set are as follows: V1 = Region where property is located (1 = North, 2 = West, 3 = East, 4 = Central) V2 = Property type (0 = Unit, 1 = House) V3 = Sale result (1 = Sold at auction, 2 = Passed-in, 3 = Private sale, 4 = Sold before auction). Note that a blank cell for this variable indicates that the property did not sell. V4 = Building type (1 = Brick, 2 = Brick veneer, 3 = Weatherboard, 4 = Vacant land) V5 = Number of rooms V6 = Land size (Square metres) V7 = Sold Price ($000s) V8 = Advertised Price ($000s) Column A (PN), contains the property identification numbers from 001 to 400 properties. Selecting your Random Sample and Creating your Sample Data File To select your random sample, you need: ? A printed copy of the Random Number Table handy. ? Open the PopulationPropertyData.xls file on computer screen. ? Create a SamplePropertyData Excel file and keep it open on computer screen. In order to select the sample data that will form the basis of your assignment you will need to make use of the random number table provided as a pdf file (RandomNumbers.pdf) on the Assessment Information page of the unit website.

The provided table of random numbers is, as the title suggests, a sequence of randomly generated numerical digits (0 to 9). These digits are arranged in a table with ten columns (numbered 0 to 9) and one hundred rows (numbered 01 to 00) spread over two pages.

The entries in each column of each row consist of six single digits. Your first task is to select 50 three-digit random (property) numbers ranging from 001 to 400 from the table of random numbers. The type of simple random sampling that we will be engaged in here is termed “without replacement” because we specifically do not want to allow a property number to be selected more than once.

If we allowed this to occur we would run the risk of the sample being biased and so not representative of the population. In the population, a particular property only occurs once and so it would not do to allow a particular property to occur more than once in your sample. In this way we can be more assured that the sample is typical of the population and so perform inferential statistical analyses about the population with some confidence.

In order to select your 50 random property numbers you will need to first go to a starting position row and column in the random number table (Note ~ not the population property data) defined by the last three digits of your VU student identification number (the assignment marker will check your student ID number against the three digits number you use to collect the random sample).

The last two digits of your VU ID number identifies the row and the third last digit identifies the column of your (relatively) “unique” starting position. For demonstration purposes, if the last three digits of your student identification were 7, 4 and 9 (i.e. 749), you would commence your property number selection at the starting 3 position – row 49 and column 7 of the random number table.

You are required to  colour/highlight the starting row number 49 and the starting column number 7. You should be able to see that the six digit number occupying that position is 217035. Then, moving across the row, from left to right from the starting position, examine the first three digits of each six digit number and then the second three digits in each of the columns of the table.

If any of these three digit numbers are between 001 to 400 inclusive, they are “good” numbers (the population data numbered from 001 to 400). Ignore any number greater than 400 or equal to 000. They are “not-good” numbers Continue reading across row 49 from left to right starting at column 7 as instructed, you would encounter the following three digit good numbers:

217, 035, 306, 150, … You need to record the first good property numbers, i.e. 217, and open the PopulationPropertyData.xls Excel file located on the Assessment Information page of the unit website.

On the spreadsheet, scroll down the PN column to locate 217 (note: do not select the Excel spreadsheet row number 217. Select the row with 217 in the PN column). At this row, highlight from 217 under the PN column across to the right up to the V8 column, use Cut and Paste procedure to cut the row of data and paste the data into a new Excel file (name it and save it as SamplePropertyData.xlsx).

Next is to repeat the Cut and Paste process for PN 035, and for PN 306 and the subsequent three digit good numbers selected from Random Number Table up to the point when the row of the spreadsheet in the SamplePropertyData file grown up to 50 rows of data. Make sure you copy the column headings, PN, V1, … V8 into your sample data file as the heading for the columns. ……

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