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 items for their weddings. They shared this information, as well as the average cost of a wedding in 2017. See the infographic below:





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

https://xogroupinc.com/press-releases/the-knot-2017-real-weddings-study-wedding-spend/


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 artist 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, there is no measure of variability.

What does this mean? A wedding planning website that makes money by advertising things for weddings inflated the costs of weddings.

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 psychologist 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.

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