Relationship B/W SPI and Total Float

Hi,

I explored the relationship between schedule performance index and total float and found,

CASE NO 1.

SPI < 1 then,

i) TF = 0 (It means on schedule but delay in non-critical activities)

ii) TF > 0 (It means ahead of schedule but delay in non-critical activities)

iii) TF < 0 (It means behind the schedule and delay in both critical and non critical activities)

CASE NO 2

SPI = 1 then,

i) TF = 0 (On schedule)

ii) TF > 0 (It means ahead of schedule but critical activities are on schedule)

iii) TF < 0 (It means non-critical activities on schedule but critical activities are delayed)

CASE NO 3

SPI > 1 then,

i) TF = 0 (It means on schedule)

ii) TF > 0 (It means bot critical and non critical activities ahead of schedule)

iii) TF < 0 (It means non critical activities ahead of schedule but critical activities are delayed)

The major purpose for sharing this information is to correct myself if i am wrong. It will be appriciated if someone give his time to read and varify. Thx