Mean projected distance between knots, , vs. the mean velocity of knots, ΔV_lobe, for 21 outflow lobes with at least 2 knots. Error bars represent the ± 1σ dispersion. Measurements and core numbers are indicated in red for outflow lobes discussed below. (a): blue lines locate the measurements for the mean inclination angle of a random distribution of outflows (57.3°) and for the inclination angles of the first and last quartiles (41°, 76°), assuming a constant variability timescale of Δt_corr = 500 yr. (b): blue lines locate the measurements for the median timescale difference between knots, Δt_corr = 500 yr, and the first and last quartiles (Δt_corr = 400 and 800 yr), assuming a constant inclination angle of 57.3°.