In: Statistics and Probability
The data below lists the population of the United States each year from 2000 until 2010. (Hint: see Chapter 7 Project Part 1) a. (4 points) Use EXCEL to make a scatter plot and find a linear model of your data. Let the horizontal axis represent the years after 2000 (the year 2000 would be 0) and let the vertical axis represent the US population in millions. Provide a title for your graph, label both the vertical and horizontal axes, and make sure the linear model is included on your graph. Copy the scatter plot with the linear model and paste it into your document. b. (3 points) Identify the slope and y-intercept of your linear model and explain what both of these values mean in the context of the data given labeling with correct units. Please use complete sentences. (hint: see last page of part 1 of the project). Year US Population in Millions 2000 282.16 2001 284.97 2002 287.62 2003 290.11 2004 292.81 2005 295.52 2006 298.38 2007 301.23 2008 304.09 2009 306.77 2010 309.3
Year | US Population(In Millions) |
2000 | 282.16 |
2001 | 284.97 |
2002 | 287.62 |
2003 | 290.11 |
2004 | 292.81 |
2005 | 295.52 |
2006 | 298.38 |
2007 | 301.23 |
2008 | 304.09 |
2009 | 306.77 |
2010 | 309.3 |
Estimation Method in Excel (Manual as well as by using formula)
Linear Model | |
y=aX+b | |
a | b |
2.728364 | -5174.645455 |
Formula Used | |
= Linest([y value range],[x value range]) |
(Make sure to select two cells to use this formula and press ctrl+shift+ Enter to execute the formula)
Manual Method
The independent variable is YearsYears, and the dependent variable is US PopulationUSPopulation. In order to compute the regression coefficients, the following table needs to be used:
Years | US Population | Years*US Population | Years2 | US Population2 | |
2000 | 282.16 | 564320 | 4000000 | 79614.2656 | |
2001 | 284.97 | 570224.97 | 4004001 | 81207.9009 | |
2002 | 287.62 | 575815.24 | 4008004 | 82725.2644 | |
2003 | 290.11 | 581090.33 | 4012009 | 84163.8121 | |
2004 | 292.81 | 586791.24 | 4016016 | 85737.6961 | |
2005 | 295.52 | 592517.6 | 4020025 | 87332.0704 | |
2006 | 298.38 | 598550.28 | 4024036 | 89030.6244 | |
2007 | 301.23 | 604568.61 | 4028049 | 90739.5129 | |
2008 | 304.09 | 610612.72 | 4032064 | 92470.7281 | |
2009 | 306.77 | 616300.93 | 4036081 | 94107.8329 | |
2010 | 309.3 | 621693 | 4040100 | 95666.49 | |
Sum = | 22055 | 3252.96 | 6522484.92 | 44220385 | 962796.1978 |
Based on the above table, the following is calculated:(in excel)
Therefore, based on the above calculations, the regression coefficients (the slope m, and the y-intercept n) are obtained as follows:
US Population(in Millions) = −5174.6455 + 2.7284*(Years)
Interpretation
For Slope
When there is increase in one year(X value) then there is 2.7284 times increase in the US population(in millions).
For intercept
The intercept (often labeled the constant) is the expected mean value of Y when all X=0.
Here intercept values is negative which do not have physical Interpretation in this context but it says that when year is 0 the population values is negative 5174.6455 (in millions).