Saturday, October 13, 2018

The Knot's Real Wedding Study 2017

The Knot, a wedding planning website, collected data on the amount of money that brides and grooms spend on different parts of the wedding. They shared this information, as well as the average cost of a wedding in 2017.

BUT WAIT! If you dig into this data, you'll find out that they only collected price points from couples who ACTUALLY PAID FOR THOSE PRODUCTS.

Problems with this data to discuss with your students:
1) No one who got stuff for free/traded for stuff would have their $0 counted towards the average. For example, one of my cousins is a tattoo artists and he traded tattoos for use of a drone for photos of their outdoor wedding.
2) AND...if you didn't USE a service, your $0 wasn't added to their ol' mean value. For example, we had our wedding and reception at the same location, so we spent $0 on a ceremony site.
3) As pointed out by Stephen Chew on Twitter, their is no measure of variability.

What does this mean? A website that sells All Things Wedding inflated the costs of weddings. Which is not great shock.

How to use in class:
a) A great example of bending the truth with actual data points.
b) An example of averages.
c) Why didn't they use median values?
c) If you are a social psychologists teaching stats, this example illustrates how data can be used to create a social norm ($33K wedding) and that norm can be used to exert pressure on people to spend more money at their wedding.

Sunday, October 7, 2018

Two great websites that generate data sets for teaching.

Or, I guess, you could use these websites to generate totally unethical data for publication. Don't do it, buddy.

Sometimes, when you are teaching, it is just nice to have some data generated so that you can teach your stats class. You know, data for a particular statistical test, and you know the results. Here are two websites that do just that.

My tried and true resource for was created by I/O psychologist Richard Landers. I blogged about this one back in 2013 and I've been using his data generator for years.

My new resource is from social psychologist Andrew Luttrell.

Nice things about both:

-Both are easy to use.
-Specific data for everything you teach in Intro Stats, like t-tests, ANOVA, correlation, regression.
-They are both free and help you do your job. Thanks, Richard and Andrew!

-Nice thing about Richard's: It gives you options of several different units (days, money, etc.) AND vignettes that explain why this data was collected. You can generate data for chi-square.

-Nice things about Andrew's: Graphs out your results. You can specify the mean and SD for the groups being compared, so you have more control over the units and come up with your own back story.

How to use either in class:

-Make up real fake data that replicates the findings of fake or actual research.

Real data example from NPR.
Pretend data example from The Onion.

-These two data generators generate the conclusions for the test. So, give your students the links so they can generate data sets and analyze it themselves.

-Handy for writing exam and homework questions.

Wednesday, October 3, 2018

Really funny Tweets about Statistics

I've shared these on my Twitter feed, and in my blog post dedicated to funny stats stuff, but I decided that it would be useful to have a dedicated, occasionally updated blog post dedicated to Twitter Statistics Comedy Gold.

How to use in class? If your students get the joke, they get a stats concept.

*Aside: I know I could have embedded these Tweets, but I decided to make my life easier by using screen shots.

How NOT to write a response option. 

Real life inter rater reliability
Scale Development