Upper left: TTV (squares) and TDV (diamonds) for Kepler-6b (see Section 2.3.1 for details). Upper right: TTV periodogram (solid) and TDV periodogram (dashed) for Kepler-6b, calculated using a sequential F-test (see Section 2.3.2 for description). Lower left: transit depths from individual fits of Kepler-6b (see Section 2.3.1 for details). Lower right: "phasing" of Kepler long-cadence photometry for Kepler-6b (see Section 2.3.4 for description).