are106-homework-6-answers - Econometrics Homework 6 ARE 106...

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Econometrics Homework 6 ARE 106 Fall 2008 A. Havenner DESCRIPTION: Vostok Ice Core Data for 420,000 Years Isotopes of Hydrogen and Oxygen have been used to develop Earth temperature histories extending over 400,000 years. The variable GT4 consists of time series data on global temperature 1 for the last 420,000 years as estimated from deep drilled cores at the Vostok station in Antarctica. See, for example, http://en.wikipedia.org/wiki/Vostok,_Antarctica . The dataset was obtained from the National Oceanic and Atmospheric Administration and is available at ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/vostok/deutnat.txt along with their variable descriptions. 2 Here we are simply looking at temperature, and not its relation to CO 2 . For a nicely objective look at these data and their relation to CO 2 see the MIT student report at http://web.mit.edu/angles2008/angles_Emmanuel_Quiroz.html The beginning of the homework as assigned The Gretl dataset Vostok.gdt has been emailed to you. It contains time series data on two variables, TIME and GT4. The variable TIME is a technically adjusted version of time, and we will use it as the time axis. (Because the time axis is adjusted, the years 2001 to 5311 that Gretl assigns to a time series plot are meaningless and should only be interpreted as arbitrary observation indexes.) The variable GT4 is not identified. While I normally will not run a regression without identifying the variables and much more, in this case it may prove interesting and so I will ask you to do it. 1. Use an X-Y scatter plot to plot TIME on the X axis and GT4 on the vertical axis. Print this plot and paste it into your homework. Examine the plot: what do you see? 1 The temperature measure is “Temperature difference wrt the mean recent time value” as reported. Subtracting a constant does not change the interpretation of the time coefficient so we can ignore this adjustment. 2 Note that NOAS’s text description of the columns does not match the column identification of the actual data.
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0 [COMMENT "Cycles, with 5 peaks, of which the latest is declining after not reaching prior maximums. There may be a slight tilting upward, not because of the maximums which are low, high, low, high, low, but rather because of the minimums, which slightly tilt up. The middle is indeterminate. Objectively, there is nothing in this plot to suggest that the last upswing is any different from the earlier ones (to my considerable surprise).”] 2. Run an Ordinary Least Squares (OLS) regression relating GT4 as the dependent variable to a constant and TIME as the independent variables, and report the results in standard format.
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