The tip to tip weld chart will state that the graph represents a "R Measure for Schedule 1" and that it represents an Offset Measurement. You can see that the resistance offset measure is 62 micro ohms.

If the wires of tip voltage measurements were open or reversed polarity, the value of offset measure would be off the chart and would be displayed as 1000 micro ohms. Make sure that the resistance offset measurement is a reasonable value.