The Phillips-Perron test output for an observed time series appears below.  Based on this output, is it likely that differencing could be useful?  How many times?  Explain.   

The ADF test output for an observed time series appears below. Based on this output, is it likely that differencing once (a first-difference) would be useful?  Explain.

Time series, cross-correlation, and ACF plots for series A and series B are below.  How much is the approximate lag between the two processes? 

Answer the following questions about the influenza virus: Explain why a different influenza vaccine is necessary every year  How does the yearly version of the organism differ from the development of pandemic versions?  Please include in your answer the terms antigenic shift and antigenic drift.

Consider the ACF plots of the residual series and the squared residual series for a time series.  Is the time series a suitable candidate for an ARCH/GARCH model?  Explain. 

Antagonist antibodies are characteristic of what autoimmune disorder?

Time series, cross-correlation, and ACF plots for series A and series B are below.  The ACF plot for series A indicates it could be modeled as an MA process.

Time series, cross-correlation, and ACF plots for series A and series B are below.  Series B appears to be trending upward until about 2015.

The surface area of the mucosa is ____ that of the skin.

You are more likely to develop MS if you live ____ the 37th parallel.