The presence of both a credible periodicity in the Lomb-Scargle Periodogram (LSP) of [(O-C) vs. Time] ("TTVxy") data points [1556.73 days, FAP: 2.898 x 10^-5] along with a sinusoidal distribution of the same points displaying a corresponding periodicity, "P_ttv"[~ 2414.67 days] (see Figure below), is strongly suggestive of the presence of an unseen (non-transiting), gravitationally perturbing planetary object(s) in this system. However, when periodicity values from both methods are large and visually obvious, the periodicities may not correspond very closely to one another if considerably less than one cycle of periodicity has been observed. This condition would significantly affect both the choice of "best-fit" sinusoidal curve and the precision of the LSP periodicity. This is apparently true for KOI-75.01.
The TTV is derived from Q0-Q17 Short-Cadence SAP_Flux Kepler data; this allowed for 13 valid mid-transits; the PDCSAP_Flux data only provided 10 valid mid-transits. x-axes: “Observed Tc” (Mid-Transit Time): EXOFAST’s best-fits from Normalized PDCSAP_FLUX Kepler light flux vs. time (BJD_tdb - 2454900) data. y-axes: “(O-C)”: difference between Observed Tc and the Calculated Tc from the graphically obtained linear ephemeris.
Figure: KOI-75.01, P = 105.88 days [Plot avg. error bars = ± 0.80 min. (smaller than symbols)]
TTV_maximum: 782.42 ± 530.38 days, Amp_ttv_maximum: 15.28 ± 30.35 min.
P_ttv: 2414.67 ± 1158.43 days (typical for <<1 P_ttv cycle).