Data required to reproduce the key results in: "High-accuracy determination of Paul-trap stability parameters for electric-quadrupole-shift prediction", J. Appl. Phys. 132, 124401 (2022). https://doi.org/10.1063/5.0106633 The file "sec_freq.dat" contains measured secular frequencies, the rf frequency, the applied bias voltages, and the MJD of the measurement: Figures 4-5 use rows 31-33 of this data. Figure 6 uses all data corresponding to -1.1e-3 < ax < -0.6e-3. Figure 7(a) uses all the data. The file "data2021-12-21_MJD.txt" contains the secular frequency data used to derive Eq. (16) and plot Figure 8. The file "RF_monitor_rectifier_1d.txt" contains the rectified monitor voltage used in Figure 8. The file "Temperature_108_1d.txt" contains the helical-resonator temperature used in Figure 8. The file "Fig9_EQS.dat" contains the measured electric quadrupole shift (EQS) used for Figure 9. The file "interleavedEQS.dat" contains the data from the interleaved EQS measurement used to determine a lower value of 1070 for the cancellation factor.

This work was supported by the projects 18SIB05 ROCIT and 20FUN01 TSCAC, which have received funding from the EMPIR program co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation program. This work was also supported by the Academy of Finland (REASON, decision 339821) and is part of the Academy of Finland Flagship Programme "Photonics Research and Innovation" (PREIN, decision 320168).