Table 4: An overview of the models for the selection effects used to generate simulated observations of simulated OB associations, for the six major datasets discussed in Sects. 4.1 to 4.6. The sample bias, resulting from the choice of the sample alone, includes the observer's choice and the brightness constraint. All other constraints result from the properties of the telescope, detector, atmospheric conditions, and confusion with background stars, and are in this paper referred to as the instrument bias. For a detailed description of the constraints mentioned in this table we refer to Sect. 4.5 of Kouwenhoven (2006).
KO5 - (Kouwenhoven et al. 2005) - Visual binaries
Observer's choice A and late-B members of Sco OB2
  (incl. Hipparcos completeness)
Brightness constraint $5.3~\mbox{mag} \leq V_1 \leq 9.5~\mbox{mag}$, $M_1 \geq 1.4 ~{M}_\odot$
Separation constraint Eq. (7)
Contrast constraint Eq. (4)
Confusion constraint $K_{\rm S,2} \leq 12$ mag
KO6 - (Kouwenhoven et al. 2007) - Visual binaries
Observer's choice A selection (11%) of the KO5 sample
Brightness constraint $5.3~\mbox{mag} \leq V_1 \leq 9.5~\mbox{mag}$, $M_1 \geq 1.4 ~{M}_\odot$
Separation constraint Eq. (10)
Contrast constraint Eq. (8)
Confusion constraint Not applicable
SHT - Shatsky & Tokovinin (2002) - Visual binaries
Observer's choice B members of Sco OB2
  (incl. Hipparcos completeness)
Brightness constraint $V_1 \leq 7.0~\mbox{mag}$, $M_1 \geq 3.5 ~{M}_\odot$
Separation constraint Non-coronographic mode: Eq. (11)
        (idem) Coronographic mode: Eq. (14)
Contrast constraint Non-coronographic mode: Eq. (13)
        (idem) Coronographic mode: Eq. (15)
Confusion constraint $K_{\rm S,2} \leq 12$ mag, $J_2 \leq 13$ mag,
  and $J_2-K_{\rm S,2} < 1.7$ mag
LEV - Levato et al. (1987) - Spectroscopic binaries
Observer's choice B members of Sco OB2
  (incl. Hipparcos completeness)
Brightness constraint $V_{\rm comb} \leq 8.1$ mag, $M_1 \geq 3 ~{M}_\odot$
Contrast constraint Not applicable
Amplitude constraint     Spectroscopic bias model SB-W
Temporal constraint     with T=2.74 year, $\Delta T = 0.38$ year,
Aliasing constraint     and $\epsilon_{\rm RV}= 3.1$ km s-1.
Sampling constraint Not applied
BRV - Brown & Verschueren (1997) - Spectroscopic binaries
Observer's choice B members of Sco OB2
  (incl. Hipparcos completeness)
Brightness constraint $V_1 \leq 7.0~\mbox{mag}$, $M_1 \geq 3.5 ~{M}_\odot$
Contrast constraint Not applicable
Amplitude constraint     Spectroscopic bias model SB-W,
Temporal constraint     with T=2.25 year, $\Delta T = 0.75$ year,
Aliasing constraint     and $\epsilon_{\rm RV}= 1.4$ km s-1.
Sampling constraint Not applied
HIP - Hipparcos mission - Astrometric binaries
Brightness constraint Hipparcos completeness
Amplitude constraint     Classification into the
Temporal constraint     categories (X), (C), (O), or (G)
Aliasing constraint     depending on the observables
Sampling constraint     of each binary system (see Table 6)

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