Here's the power point from my presentation on the average cost of an engagement ring bought online.

1. A Statistical Study Evaluating the Average Cost of Engagement Rings Purchased Online Presented by BuyDiamondRings.org

2. Many sources have reported different numbers, ranging from $3,000 to $6,000. About.com reports that the average cost is the range of $3,500 to $4,000 (link) Learnvest.com reports that the average engagement ring in 2009 sold for $3,150 (link). TheKnot.com reports that the average cost of an engagement ring in 2010 was $5,392 (link). What’s the Average Cost of an Engagement Ring?

3. The Wall Street Journal reported in 2006 that $5,600 was the average cost for an engagement ring purchased on the net(link). I focused on online engagement ring sales for my study. I took a sample of 829 engagement rings sold online in late 2010/early 2011 and analyzed the cost data. What about online, specifically?

4. Most expensive ring: $86,829. Lease expensive ring: $698 . Mean: $8,613.26. Median: $6,071.00. Mode: $3,379.00. Standard Deviation: $8,144.90. Skew**: 3.07 ** The skew is important – notice it on the graph on the next slide. Here’s what I found…

6. As you can see, there were two things that stood out about the histogram. #1: The skewness. As reported a few slides back, there is a strong skew value of 3.07 #2: The outliers. There were numerous outlies on the upper end of the distribution. What happens when I remove the outliers? The results

7. Mean: $7,696.63. Median: $5,969.00. Standard Deviation: $5,707.24. Skew: 1.36 The mean changed drastically, but the median was almost unchanged. This is typical when there are so many outliers and a strong skewness. Here’s the graph without the outliers: Results with Outliers Removed

9. Even after removing the outliers, the distribution is still skewed. Given the skew and the outliers, the median is a better measure of the average cost of an engagement ring purchased online. In this study, the two medians were $6,071 and $5,969. Averaging these two medians out gives $6,020, almost exactly $6,000. Using these results, I would infer that the average price of an engagement ring purchased online is $6,000. Still skewed, but better…

10. This was a presentation by BuyDiamondRings.org. Data was provided by Blue Nile. If you are in the market for an engagement yourself, please read our engagement rings guide.