3. (20 points) The following data is the number of new cases per day of smallpox in the village of Abakaliki. This village had a population of 120 in 1982 when it suffered this outbreak. Data covers 29 observations over a 29 day period: (Data source: Handbook of Small Data Sets.)
13 7 2 3 0 0 1 4 5 3 2 0 2 0 5 3 1 4 0 1 1 1 2 0 1 5 0 5 5
The time series data was regressed twice, once with a constant term ($B_0$) and the other time with the constant term ($B_0$) constrained to zero. Both regressions lagged by one time period. We want to know if the data series a random walk, and is it a random walk with drift or without drift.
The time series regressions were solved as:
Solving as lagged by one time period, including the constant term:
$X_t = B_0 + B_1X_{t-1} + E$ (Where E is the error term.)
Standard errors are in parenthesis underneath.
$X_t = 1.644919 + .2386X_{t-1}$
(.502256)
(.133)
Alternatively, also solved as lagged by one time period, but in this case the constant term has been constrained to equal zero:
$X_t = B_1X_{t-1} + E$
Standard errors are in parenthesis underneath.
$X_t = .531328X_{t-1}$
(.114953)
A. Use the t table to determine of the number of new cases of smallpox is a random walk. Show your work.
B. In addition, determine if it is a random walk with drift, or without drift. Show your work.