Exercise 1 Content –Covers chapters 1-4 Chapter 1 (read) Chapter 2 (important for the exercise, 2.6 comes later) Chapter 3 (especially 3.1, 3.2, 3.5) Chapter 4 (especially 4.1, 4.3. Read also 4.6)

Exercise 1 Purpose –Getting to know SPSS –Learning: basic description probability distributions. Data –RogersonHus.sav –Turistresor.sav

Exercise 1 Deskriptive statistics One variable>1 variable, relations NumericMean Variance skewness Correlation visualBoxplot Histogram Scatterplot (two continous) Boxplots (one continous, one categorical) Tables

Exercise 1 How to do the exercises Read the book chapters Look at tutorials of SPSS if you don’t know the basics, eg: – – SS/ SS/ –SPSS Brief Guide 14.0.pdf –SPSS Base User's Guide 14.0.pdf Do the exercises with help of –Slides –SPSS help system –Each other –Me

Exercise 1 Presentation –At the presentation everyone should be prepared to show the results of the exercise in a suitable manner and discuss the findings of the other participants. –Everybody should also hand in a short written paper with relevant output, answers and conclusions.

Exercise 1 OK, lets start by saving a own copy of RogersonHus.sav and starting it in SPSS by clicking on the file The data is described on page 20 in Rogerson (House prices + other variables)

Exercise 1 One variable – The variable we want to explain is the price. On what scale is the variable measured? Do some basic descriptives of price –Mean, standard deviation, skewness –Use:Analyze>deskriptive statistics> deskriptives »Options > skewness Make a histogram of price –Use: Graph>histogram>display normal curve –What can we say about the histogram? –Compare the histogram with the descriptive statistics above. Make a boxplot of price. –Graphs >boxpot >simple> s. of separate variables –Compare the result with the other descriptive above

Exercise 1 Random numbers Assume that we want to see what a random sample with the same mean and variance could look like. Generate such a sample!

Exercise 1 Random numbers To get a fresh start of the random generator. –Transform>random number generators>set starting point>random To get the random numbers: –Transform>compute>function group:random numbers>Functions and special vaiables> RV.Normal> choose mean and standard deviation from previous description.

Exercise 1 Random numbers Do the same descriptives as before on the randomly generated variable. Answer/discuss the following questions: –Compare the results for the price data, the randomly generated data and the displayed normal curve. What can you see? Why are they different? –Look at the results for the randomly generated data. Why are the mean and standard deviation not what we simulated from?

Exercise 1 Relations Now lets turn to relations among variables. One continuous variable (price) and one categorical (number of bedrooms) -> Box plot. – Graphs >box plot >simple> s. of separate variables>boxes representant :Price > columns: bedrooms –What can we say about the relationship?

Exercise 1 Relations One continuous variable (price) and two categorical (number of bedrooms, and garage) -> –Analyze > tables > custom tables> draw the variables so that we get the average price grouped on bedrooms and garage. –Important: right click to get the right measurement level if necessary! –Interpret the results

Exercise 1 Relations Two continuous variables price vs. year built (dateblt) –Graphs>scatter>simple scatter –What can we say about the relationship? –From what you learn from the overview given in the lectures what regression method would apply in this case (Y=price)

Exercise 1 Garage Suppose that we were interested in factors that can explain if a house has a garage instead. Do a custom table to find out if district and presence of garage is related Do a histogram divided on district to show the same relationship. From what you learn from the overview given in the lectures what regression method would apply in this case (Y=garage)?

Exercise 1 Garage Find the proportion of houses that has a garage. Generate random numbers with that proportion for all data. RV.bernulli Do the same descriptives as in the previous slide. How does this compare with the previous slide? Interpret the results.

Exercise 1 Turistresor.sav Start by saving a own copy of Turistresor.sav and starting it in SPSS by clicking on the file. SFO is the number of tourism trips the individuals have made under a time period. Do basic descriptives of SFO. What is the mean number of trips the individuals have made? Do a histogram of SFO that is divided by sex (kon, men = 1). Select the men and do the basic descriptives for only the men. Selection under: data>select cases.

Exercise 1 Turistresor.sav From what you learned from the overview given in the lectures what regression method would apply in this case (Y=SFO)? Generate random numbers with the same mean as SFO using the mean of SFO and RV.Poisson Compare the distribution of the new variable with SFO. What conclusions do you make?

Exercise 1 Turistresor.sav Investigate if access to a second home (tillg1=1) affects the number of tourism trips. Do “analyze descriptive statistics” on tillg1 One problem the is evident is that only ones show indicating access to a second home Solve this problem by recode missing values in tillg1 to 0. >Transform>recode Then do the relevant descriptives.