大二上期末复习江财职协cic2013宏观chapter115课件ch01a10e lecture.pptxVIP

1;A graph reveals a relationship. A graph represents “quantity” as a distance. A two-variable graph uses two perpendicular scale lines. The vertical line is the y-axis. The horizontal line is the x-axis. The zero point in common to both axes is the origin.;Economists measure variables that describe what, how, and for whom goods and services are produced. These variables are quantities produced and prices. Figure A1.2 shows two examples of economic graphs.;Figure A1.2(a) is a graph about iTunes song downloads in January 2010. Point A tells us what the quantity and price were. You can “read” this graph as telling you that in January 2010: 8.3 million songs a day were downloaded at a price of 99￠ per song.; ;Scatter Diagrams A scatter diagram plots the plots the value of one variable against the value of another variable for a number of different values of each variable. A scatter diagram reveals whether a relationship exists between the two variables. Figure A1.3 (on the next slide) shows some data on box office tickets sold and the number of DVDs sold for nine of the most popular movies in 2009. The table gives the data and the graph describes the relationship between box office tickets sold and DVD sales.;Point A tells us that Star Trek sold 34 million tickets at the box office and 6 million DVDs. The points reveals that larger box office sales are associated with larger DVD sales.;Figure A1.4(a) is a scatter diagram of income and expenditure, on average, during a ten-year period. Point A shows that in one year, income was $31 thousand and expenditure was $30 thousand. The graph shows that as income increases, so does expenditure, and the relationship is a close one.;Figure A1.4(b) is a scatter diagram of inflation and unemployment in the United States during the 2000s. The points for 2000 to 2008 show no relationship between the two variables. But the high unemployment rate of 2009 brought a low inflation rate that year.;Graphs are used in economic models to sh