The myth of the 100-year flood

Casual handling of statistics make me cranky.  So we take a break from job-seeking and a SQL tutorial for this public service announcement about the so-called 100-year flood.

WaPost's Five myths about Hurricane Katrina included this tidbit:

4. New Orleans’s levees are fixed and could withstand another Katrina.
After Katrina, Washington committed $14.5 billion to flood-protection improvements that are supposed to survive a 100-year storm — a term of art that refers to storms that have a 1 percent chance of striking in any given year.

Kudos to writer Jed Horne for using "term of art" to emphasize that the term has a specific actuarial and regulatory definition.

Unfortunately, most people are not so careful.

If an area has a 1% chance of flooding each year, it does NOT mean that it will flood once per century.

I fired up python in an OS X terminal, but you can use any calculator or programming language you like to replicate these results.

Assuming each year is independent of every other year, you have a 99% chance of NOT being flooded in any given year.  Over a 100 years,

>>> .99**100

0.3660323412732292

you have a 36.6% chance of escaping flooding.
You also have a 1 - 0.3660323412732292 = 63.4% chance of being flooded at least once per century.

Over 50 years,
>>> .99**50
0.60500606713753635

you have a 60.5% chance of escaping flooding.

Conversely, you have a 1 - 0.60500606713753635 = 39.5% chance of being flooded at least once.

Suppose you have a 2% chance of flooding each year.  Over 100 years, 

>>> .98**100

0.13261955589475294

you have only a 13.3% chance of escaping flooding.

Hey, that doesn't scale (linearly)!  ;-)

The power of powers never ceases to amaze.

You may also want to read What planet are they on? for another illustration of nonlinear phenomena.

FIFO or LIFO?

How do you use your collections?  First In-First Out?  Last In-First Out?

Sometimes, I sew the latest fabric purchase on top of the stack.  Other times, I rummage through the bins for a specific color and unearth pieces purchased long ago.  This project is LIFO because it was sewn up within a week of arrival.

I purchased this costly Liberty of London Tana Lawn during my last visit to Elfriede's Fine Fabrics in August.  (BTW, though the fabric is costly by my standards, it was only $40/yd at Elfriede's for the 54" Tana Lawn vs. $50/yd I've seen elsewhere for the exact same thing.)

I purchased 3/4 of a yard, or $30 worth because it perfectly matched a cardigan I was knitting at the time, I love the feel of Tana Lawn, and the shell in Vogue 1071 uses the fabric very efficiently. 

The last time I made this blouse, it rode up slightly at the hips.  For this version, I added about 1.5" around the hips and it fits much more smoothly.  Of course, I only have photos of it worn tucked in so you can't see that. ;-)

You can see the nice buttons that I recycled from an old and (sadly) shrunken linen blouse (another Calvin Klein pattern).  The front is lined with red/white cotton batiste rescued from the SBQG share table.  I like this blouse so much, I pulled out a cotton lawn remnant purchased from Poppy Fabrics about 25 years ago to make another!  If that is one of the oldest fabrics in my collection, does that make it FIFO?

It's a high-low outfit because I purchased the skirt fabric from barrels at Trash For Teaching for $1/pound. The fabric is factory waste from American Apparel; their factory is only a few miles from T4T.

At T4T we strive to source wonderful, clean, safe, interesting items that local businesses discard in abundance, and make them available to shoppers at the warehouse. Over the past 8 years we’ve collected materials from over 200 companies, most of those original manufacturers still donate to T4T today. Since we first opened our doors in 2004, T4T has diverted over 50,000 pounds of materials from local landfill. Those materials include an abundance of plastic and cardboard thread cones, in all colors shapes and sizes, beautiful wood from a shutter company, plastic color chips, glass tubes, fabric and trim, colorful rubber mats, tiles, tubes, Styrofoam….and the list goes on.

BTW, if you are visiting LA and have a rental car, it's worth visiting T4T and exploring their warehouse neighborhood (near the intersection of I-110 and I-105) to learn just how much (besides celluloid) the region manufactures.  T4T also sells science "teacher kits" made up of trash with lesson plans at bargain basement prices.  The kit for teaching optics is genius!  I say that in earnest.

Anyway, the linen was celadon green and the jersey was light olive green.  I dyed the linen to match the jersey and then lined it with gray rayon lining, which deepens the green of the linen.  Notice also that the hip yoke has darts incorporated into the seams.   The linen is cut on the bias.  I drafted the pattern.  I made a bias top to go with it.  The set deserves it's own post at a later time.

Loop

I succumbed to impulse purchases at Elfriede's Fine Fabrics this summer.  This 1/2 yard piece of 54" wide silk shot chiffon (fuchsia in one direction, black in the other) was only $4 so it came home with me.  It would have made a rather short scarf on it's own.

But, then I saw Habu N-80, a silk-wrapped merino yarn, at Twist during their summer sale.  I bought a 1 oz skein (187 yds), cast on 40 sts and knit in elongated seed stitch on size 7 (4.5 mm) needles until I ran out of yarn.

I sewed the chiffon into a tube in the long direction and inserted the knit piece in between the short ends to form a tube about 80" in circumference and 9" wide.  It can be worn looped three times (above) or twice (below).

I just love the textural contrast between the smooth chiffon and the seed stitched wool.  The wool is surprisingly not scratchy after I washed and blocked it (before sewing it to the chiffon).

Does your stash grow while you sleep?  I do not understand how this ~2 yard piece of silk came to be in my luggage.  When I unpacked my purchases from the trip, there it was.  Where did it come from?

@ Shams: The silk was folded up in a 1 quart ziploc bag, which stores don't usually use.  It's extremely odd.  I don't think that Stone Mountain and Daughter gifted this to me--though, in the 1980s, they used to gift me quite a bit of fabric with their generous cuts.  I actually thought that I was able to buy 1/4-1/3 less fabric all the time because I was so efficient with layout.  Another seamster insisted that I measure my fabric and she was right.  Remember the rule about "a yard and a thumb"?  Well, the cutters at SM&D had very fat thumbs for their regular customers.  I shopped there both for my personal needs and for the costume shops of Berkeley Shakespeare and Repertory so the cutters knew me.