## What does statistical significance mean?

One of my students sent me this article because we spend some time in class covering Type 1 and Type 2 errors.

All the .05 threshold means is that you have a false positive 1/20 times.  A .005 threshold would say you’re getting a false positive 1/200 times.  So by moving to a .005 threshold, you’re less likely to get a false positive.  That’s good, right?  In common parlance, we’d be less likely to send an innocent person to jail.

Well, that depends.  At the .005 threshold, we’re more likely to get a false negative than you would at the .05 level.  That means we’d be more likely to get a guilty person go free.  (Indeed, the only guaranteed way to send no innocent people to jail would be to send nobody to jail.  I, for one, am happy that folks like Charles Manson are behind bars.)

It isn’t as easy as saying, oh we should just switch to .005.  When you adjust the p-value you’re making trade-offs between type 1 and type 2 error.  With a lower p-value threshold you’re going to be getting a lot more false negatives even with fewer false positives.  What we always need to be cognizant of when we’re doing policy is that significance isn’t everything– we also have to think about what the damage is if this information turns out to be incorrect.  For example, doctors recommend that pregnant women should heat up cold cuts if they’re worried about listeria, which is a very low probability event but if it happens it’s horrible.  It’s pretty easy to avoid room temperature cold-cuts for 9 months, so unless there’s some other difficulties attached to diet, women will probably follow this recommendation.  (And if one accidentally eats room temperature coldcuts while pregnant, one shouldn’t freak out because the probability of getting listeria is very low!)  But if we’re talking about something like doing chemotherapy or surgery, that’s a much more onerous action and we might want to be more sure we need it before going ahead with it.

Another thing to note is that the article talks about how physics and genetics have already made this switch, while most social sciences haven’t.  One big difference between the fields that have made the switch and the fields that have not is how easy it is to get large samples.  A larger sample size will make it so your sample behaves more and more like the population that you’re trying to study.  We can reduce both Type 1 and Type 2 errors simply by increasing the sample size.  So why don’t we do that?  Well, it turns out that increasing the sample size can be very very expensive when you’re dealing with people and behavior.  Sometimes doing the study with a large enough sample to get 80% power and an alpha of .005 might be more expensive than just throwing that same money at the intervention you’re trying to decide about, whether or not it actually works.  There probably is some resistance because people in these fields want to be able to publish their 5% results, but that’s not the main or only reason we haven’t yet made the switch.  Research is complicated and expensive and we have to make trade-offs.

The context for these really does matter, and you shouldn’t necessarily put off making policy choices just because your sample size is too small to get significance (or to make policy changes just because you have significance).  You always have to be aware of the costs and the benefits.

(Incidentally, in case he comes across this, Hi Dan!  I’m assuming that the reporter greatly simplified your arguments here because I know you must know this stuff.)

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## Things that negatively affect my mood

Lack of sleep

Lack of a feeling of control/feeling overwhelmed/being told I have to do stuff or that I’m not doing enough stuff

Having future deadlines but not being able to work on them even though I planned to work on them because other people have dropped the ball and there’s nothing I can work on in the meantime while I wait because I already did it all or I would have to get into the mindset for a completely different project and I just don’t have that mental load and I know everybody is going to get back to me at the same time too close to multiple deadlines and I’m going to be stressed out.

Eating sugar or refined carbohydrates and sugar-crashing

Low blood sugar more generally

Mild tummy aches/headaches

impatient drivers behind me who want me to risk my life making a left turn across traffic

Sometimes hormonal imbalances

Whining (other people’s not my own, and literal whining)

Mansplaining

Did I mention people flaking out on me?

Grumpy nation, what harshes your buzz?

## I hate deadlines

My family is at a last minute high tea and gaming party without me.
I was invited too but I have to finish this stupid report due Monday that I didn’t get the data for until yesterday afternoon.
I hate last minute deadlines.

My coauthor’s all, “Last minute deadlines are the only way I ever get anything done.”

I HATE them.
I like getting my work done between the hours of 8am and 5pm.
M-F
and outside of that only if I WANT to, not because there’s some last minute I’m scrambling deadline
because I always screw up when I’m scrambling
(I probably screw up when I’m not too, but I find and fix those screw ups in time.)
(with nobody the wiser)
Also scrambling negatively affects my sleep (guess who woke up at 5am?)
How do you feel about deadlines?  Do they mess you up or do they increase your productivity?  Do you get things done ahead of time when you have all the bits and pieces or are you always scrambling?

## Thoughts on professional cleaners

After putting our house on the market, we hired professional cleaners because we couldn’t keep up with keeping the house spotless on top of everything else.  Normally we live in squalor and we’re fine with that (so long as there’s no mold or anything growing).  But when you’re regularly showing a house and the people you have a verbal agreement about the lease with drag their heels for a month, it’s best not to have deep cleaning on the list of things to constantly worry about.

The first person we tried charged \$120/session (so ~\$60/hr), which we would have been fine with if she’d done a good job cleaning.  But she didn’t.  There were crumbs on the dining room table, dust on the bookcases, toddler hand prints on the windows, cat hair on the carpet and in tumbleweed form and on and on and on.  I came home and couldn’t tell anybody had been there to clean, except she’d apparently spent a large amount of time scraping soap out of a soap holder (but not cleaning any of the rest of the shower).  Even more than I hate spending money on things I don’t value, I hate spending money and not actually getting what I don’t value.  I hate paying someone a lot of money for something I could do myself and then I have to do it anyway.  If I’m paying a lot of money, they should do as good as or better than I do.

So then we tried a local agency (that everyone who doesn’t use the lady we tried first uses), bonded, insured, etc.  \$175 for the first clean, \$100 for a weekly clean.  They left the place mostly clean and I could tell things had been cleaned when I walked in the door.

\$100-120/week is \$400-500/mo is \$5000-\$6000/year.  We could give someone at DC1’s school an 80% scholarship for \$6000/year.  It’s such a waste for something we don’t even need and I don’t even get to feel noblesse oblige about paying for it because most of that money is probably going to the owner of the company– the women who actually do the cleaning are not getting \$100/clean.

Also I don’t like the smell of cleaning products.  And it lasts for two days after they’ve come.  And a few times they’ve come after 5:30 on Friday, which means I’m home while they’re cleaning which hurts my midwestern sensibilities– I feel like I can’t just kick back and relax (or make dinner because they clean the kitchen last) and I should be cleaning too, which is ridiculous.

So that’s me being grumpy.   DH, of course, likes having the cleaners, probably because he’s the one who usually does the bulk of the cleaning given my dust allergies.

Do you have someone clean the house?  Do you love it?

## When to replace a car?

Just got a \$1000 repair estimate for my \$3000 blue-book value car.  (\$500 in absolutely necessary to turn the check engine light off repairs, \$500 to replace a couple of axles that cause vibration.)  The car is 10 years old with 36,000 miles on it.  (It’s also all shiny and clean because DH had it detailed for me as a Christmas present.)  To get a newer model of our current car would be about \$15,000.

Since we’re only taking one car with us to paradise next year (this is one of those sacrifices people make in paradise if they want to continue saving for their kids’ college, but there’s public transportation so it’s not so bad), if we do decide to get rid of the car, this summer would be a good time to do that so we don’t have to find a place to store it.

In the past, my rule had been to replace a car when the cost of repairs was greater than the value of the car, but that was easy when we had a single major repair cost.  When they start coming in in drips and drabs like this it’s harder to make that comparison.  At the same time, the drips and drabs are annoying when each one means we’re down to one car for a week (I end up having to do all pick-ups and drop-offs and don’t have as much work flexibility, unless DH plays chauffer which means extra driving).  Time is money!

It’s still a good little fuel efficient car.  And it looks all shiny and new on the inside right now.  I’m a bit attached to it.

So we’re paying the \$1000 now, and we’ll rethink this after the next repair bill or it’s time to go to paradise, whichever comes first.

How do you decide when it’s time to replace a car?

## RBOC

• I was depressed for no reason for a week or two.  (Well, not no reason, I mean, there were disappointments and things, but usually things I get over.)  I thought maybe it was my diet (refined carbs had crept in), but changing that, while it helped, didn’t make it go away completely.  Then I took some of the vit D I have been supposed to be taking.  20 min later I felt back to normal.  Note to self:  Vit D.  Take it.
• I wish we could afford 6K/month in rent.  That would make a lot of things a lot easier.  [Update:  now 7K/mo in rent… housing prices be crazy.]
• What is it with toddlers and imaginary keys?  Dc2’s imaginary dragon was stuck and needed a key to get out.  At just a little bit older than this age, dc1 was pulling imaginary keys to open imaginary doors blocking hir path.  Our children are magical.
• This year we’ve gotten 3 Christmas cards for the people we bought the house from EIGHT years ago.  Usually we get one or fewer.  Hopefully the online whitepages has their “new” address correct.
• Dear retired FBI guy, I still do not know the personal schedule, cell phone number, etc. of the gentleman whose office is next to mine.  I am also still not a secretary, personal appearances (given my lack of Y chromosome) to the contrary.
• Dear students, especially those who I have never seen before in my life, you need to get a new stapler in your workroom because my stapler is not your personal stapler.  Again, I am still not a department administrative assistant, and if you’re going to turn your exam in to a department administrative assistant *anyway* then you should use her stapler.
• Dear new administrative assistant, I am having a really hard time understanding why all these people cannot find you because you are ALWAYS just across the hall from me talking really loudly to the student workers keeping anybody from getting any work done.  Maybe that’s why the guy whose office is next to mine is never here.
• So, #2 tried a more casual first paragraph in a cover letter and got a call-back almost immediately.  Trying to figure out if that’s going to work for every job or specific kinds of jobs or if it was just a fluke.
• Nice kitty currently on Prozac to see if that stops the peeing.  She hasn’t peed yet that we’ve found, but she also is spending all of her time hiding from us– she seems subdued and unhappy.
• DC2 officially started the new daycare this week!
• Age 8 seems to have replaced age 7’s sulking with annoying elementary school humor.  We think that’s a good trade.
• Alligator pear is another name for avocado.  Who knew?  (#2 did.)
• Am I the only toddler mother in the world who is not interested in talking at length about poo?  [Update:  brief survey of my coworkers suggests the answer is no.]
• One more bullet though– gotta brag about DC1 finishing Hard Math.  It really was hard!  And sooo awesome!  (Gotta tell the blog, because who else can I tell?)

## Deaccessioning: A sad post

… Not actually that sad.

Last night we laid out the space and we estimate that between the two of us we can fit in about 11 bookcases in the new apartment.

Currently we have 16 bookcases and 2 built-ins.

Oops.

We’re still working on deaccessioning the relatively easy stuff. I’m down under 1300 books, from a high well over 1500.  My partner has at least that many, too!

We’re going through by areas of the house. Some bookshelves are just full of stuff that can’t go. Others are full of chaff. So we start with the chaff.

Gonna be a lean mean LIVING IN PARADISE machine.

I discovered there are some books I was keeping out of guilt, and now I feel great about letting go of them.  I have some “I’m never going to read this” and “I read this but don’t ever ever want to read again” and “why do I have this?”  (note that it took YEARS into our relationship before I EVER felt ok about getting rid of a book he’d given me as a gift.  But now I know we just have love and a stable relationship, and there will be more gifts.)  There are also books that I realized I can get rid of because I’ve internalized the knowledge that I need from them after many years.

At some point we’re going to end up having to make hard choices. Probably what will happen is we’ll bring way too many books anyway and have to deal with it there in some way.  I’m totes gonna overfill the bookcases we have with double-stacking and all. It gonna be all jenga up inside.  And then who knows?

We could add something moralistic about minimalism or money spent or what have you, but that would just be patronizing, so we won’t bore you with that.  I HAVE NO REGRETS.  Except the regret that downsizing comes with deaccessioning, but sacrifices must be made, and there’s a good library in walking distance to our new apartment.  In the meantime, onto the next quadrant!

#2 notes that they have 13 bookcases, including built-ins, but that’s only because her partner tends to get rid of books after reading them rather than holding on to them.  (Sometimes he’ll be halfway through a new book he just bought and realize he bought it, read it, and got rid of it years ago.)  Also most of her newly purchased romance novels are on kindle.

Bibliophiles, how do you deal with not having enough space for books?