Schematics, Design & the Bell Curve

Many of knitters and crocheters – and I include myself – get rather annoyed when we pay for and download a pattern to find that it contains no schematic.  In this post I decided to discuss sketching one’s own.

LopiPictureDue to copyright issues, I needed to select a pattern that’s free.  I chose to use this pattern by Istex, offered free on its website here.  If you click on the picture, it will enlarge and you will be able to see that it is a simple raglan sweater.

The pattern is designed to use Bulky Lopi.  I thought I might adapt this pattern as the basis for a Lopi pullover for Thor.  He keeps borrowing my old (and beloved) pullover I knit over 20 years ago out of a wonderfully warm bulky Lopi in (for some reason long forgotten) the most unbecoming – to me – shade of brown.  (Of course, I wouldn’t mind another wonderfully warm and cozy bulky Lopi pullover in a color better for me.)

KnitGraphPpr32ratioOne could use Excel, though she must be sure to resize its cells in a 3:2 or 5:4 ratio – as knitting graph paper should be.  I pulled up a new Excel sheet and locked these cells into a 3:2 pixel ratio.

I then went to the Insert tab and selected Shapes and experimented with straight lines, ovals and KnitGraphPpr2scribbles to come up with this quasi-monstrosity of a sketch of a raglan.

(I know – awful.  I was always the worst student in my water color class, still life drawing and ceramics.)

Now most non-professional knitters and crocheters do not have customized designing software to use and may not be comfortable tricking Excel (a spreadsheet software) into use.  So I think it more useful to stick to the traditional way (i.e., using pencil and paper), which also happens to be my favorite mode of drawing schematics.  🙂

I pulled out a stack of lined paper and started making notes about the pattern before I started sketching.  The oddities one discovers at a closer look … curiouser and curiouser (to borrow from Mr. Carroll).  This simple pattern is a walking illustration the importance of being able to draw a schematic and knowing what and how to adjust the pattern for a good fit.

Size S M L XL
Finished chest (inches) 38 40 42 44
Length to shoulder (inches) 21.5 22.5 23.25 24
Sleeve length to underarm (inches) 19 20 20 20

First, you will note the finished chest measurements (in inches) are standard for a S-M-L-XL.  But notice the narrow incremental changes in length to shoulder and sleeve length.  The three sizes (M-L-XL) all have the same sleeve length, and the S’s sleeve length is a mere one inch shorter.

This is pattern for a woman’s sweater, but let me drag the Bell Curve into this discussion.  The Bell Curve is a graph of the normal (Gaussian) distribution; it has a large rounded peak tapering away at each end.  Bell curves follow the 68-95-99.7 rule, which means this:  Of all the data graphed in the distribution,

SD1Approximately 68% of all of the data lies within one standard deviation of the mean (i.e., between -1 and +1);


Approximately 95% lies within two standard deviations of the mean (i.e., between -2 and +2);


Approximately 99.7% lies within three standard deviations of the mean (i.e., between -3 and +3).

What does this all have to do with this post?  Let’s use me as an example.

The mean height of women in the U.S. is 5 feet 4.6 inches or 164.1 cm with a standard deviation of 3.5 inches or 8.89 cm.   My arms are in proportion to my height, and I have an extremely long torso that sits atop “average” length legs.   (I am, however, the average height of a man in the U.S.: 5 feet 10.2 inches or 178.2 cm.  Their mean height has standard deviation of 4 inches or 10.16 cm.)

  • Mean height of woman in US:  5 feet 4.6 inches (164.1 cm)
  • Standard deviation:  3.5 inches (8.89 cm)
  • The  height of 68% of all women in the U.S. is somewhere between 5 feet 8.1 inches (=5 feet 4.6 inches + 3.5 inches), or 172.97 cm, and 5 feet 1.1 inches (=5 feet 4.6 inches – 3.5 inches), or 155.19 cm.

Neither clothing manufacturers nor pattern designers have the women whose heights fall outside of one standard deviation above or below the mean in mind.

cartoon heightLook back up at the second bell curve above.  See the space between +1 and +2 standard deviations?  Women my height fall into that space.  Women who are shorter than 5 feet 1.1 inches (155.19 cm) tall are in the space between -1 and -2 standard deviations (i.e., below the mean). (pic source)

Now that I’ve gotten a bit off track … to be continued in my next post.


About sweatyknitter

Fiber art devotee, author, and amateur artisan bread baker.
This entry was posted in Bulky Lopi, Crocheting, Knitting, Pattern Construction, Sweater Design and tagged , , . Bookmark the permalink.

8 Responses to Schematics, Design & the Bell Curve

  1. Noddfacrafts says:

    You are so clever! I’m very impressed!


  2. myraho78 says:

    I love you post! your through instruction must be very helpful to many knitting lovers. I was one of they! Ever since 14 years ago due to the stroke my left side went to sleep. I can’t either knit or crochet any more. Thank God my right hand still works!
    Would you be interested to drop by my blog, you’ll see some different kind of crochet works done by my mother.
    I thought I was going to do it after I retired, but two months before I retired, stroke got me………


  3. I share your desire for the, as you called it, “meta perspective.” I need to see a schematic! I used to do a lot of sewing and tailoring in my youth, and between growing up on the old abbreviated Norwegian patterns with a good schematic and later focusing on the technical designs of a sewing pattern … Like you, I rewrite a lot of patterns, though I will not pay for a pattern without a schematic (unless it is well written and provides a lot of detail for patterns that are quite good – like Kate Davies’s book “Yokes.”). After drawing a schematic and rewriting pattern instructions, I find myself asking, “Why am I doing someone else’s work?!” The Istex pattern that I’m using as an example in this blog and the following I probably won’t knit after all is said, done, revised and remedied … I’ll just calculate and knit my own I think.



  4. Suzan says:

    Many thanks for this post – and I totally agree! I hate when there are no schematics – with measures or schematics for pattern / lace / cables. As I just recently (i.e. approx. 2 years ago) started knitting after English patterns, it took me a while to learn to knit just from written instructions. As a visually oriented person I always need to understand the basic concept and construction of a project – the meta-perspective, so to say, before I get to the details. Just narrative format is hell for me. 🙂 (just experienced it with Stephen West’s Sharktooth. I rewrote the pattern and it took me ages…)


  5. Thank you … Though I’m sure more than one reader saw the graphs and thought, “where is the woman going with this?” 🙂


  6. I agree that it is important for a pattern to be well written and easy to understand. However, if a knitter wants to anticipate revisions and adjustments, a schematic is invaluable. Of course, how one learned to knit undoubtedly plays a part. Every knitter in my family used abbreviated Norwegian patterns and adjusted to graphs. The first time I saw a pattern in the narrative format – I think it was British – I was flummoxed! 🙂


  7. Tina says:

    Interesting post. For me personally do not care if there is a schematic or not. I’m more interested in how the pattern is written and how easy it is to understand.

    Liked by 1 person

  8. Really interesting and helpful…looking forward to the next post! Thanks, Sarah


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