Twist Collective

Slip, Slip, Slip, Purl (sssp)

This is a left-leaning decrease.
It looks the same on the right side as sssk, and sl1, k2tog, psso.
It mirrors with the right-leaning decrease p3tog.
 

Slip three stitches, one at a time as if to knit.
 

Slip the three slipped stitches back to the left needle in their new orientation.

Purl them together through the back loops.

Decrease How Tos:

Right-Leaning Single Decreases
Knit Two Together	Purl Two Together
Left-Leaning Single Decreases
Slip, Slip, Knit	Slip, Slip, Knit Variation	Slip, Slip, Purl
Knit Two Together Through the Back Loops	Purl Two Together Through the Back Loops	Slip, Knit, Pass Slipped Stitch Over
Right-Leaning Double Decreases
Knit Three Together	Purl Three Together
Left-Leaning Double Decreases
Slip, Slip, Slip, Knit	Slip One, Knit Two Together, Pass Slipped Stitch Over	Slip, Slip, Slip, Purl
Centered Double Decrease
Centered Double Decrease

Read the full article, Decoding Decreases
Download a handy pdf with Decoding Decreases and instructions for all of the decreases. 

Sandi Rosner is a knitter who wears many hats: designer, technical editor, writer and teacher. She loves the little details that elevate a knitting project from homemade to handmade. Follow Sandi’s blog at knittinginwinecountry.blogspot.com.