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Table 1 Statistical process control (SPC) analysis of the data on the individual farm level

From: Assessment of immediate production impact following attenuated PRRS type 2 virus vaccination in swine breeding herds

Production parameter Frequency of signalsa Duration of signals Magnitude of signals
Abortion rate 4/65 (6.1%) 1 to 7 weeks 0.11 to 0.16%
Neonatal losses 5/65 (7.7%) 1 to 5 weeks 0.34 to 1.85
Pre-weaning mortality 2/65 (3.1%) 1 to 5 weeks 3.99 to 5.21%
Total pigs weaned 0/65 (0.0%) N/A N/A
Wean-to-first-service interval 2/65 (3.1%) 3 to 5 weeks 1.03 to 1.44 days
  1. a = A decrease in productivity following each MLV intervention, with performance parameters crossing the EWMA control limits, was defined as a signal