Biabreakable
Footballguy
Is it dishonest to remove these outliers from our data? My initial reaction was to stay yes, of course it is wrong to remove outliers, they are part of the data set so their presence must have a purpose! Therefore removing these data points and going on to prove your hypothesis would be dishonest because in the absence of the outliers, the results presented aren’t your actual results. However I now believe outliers caused by anything but chance must be removed from the data set.
Some believe outliers shouldn’t be removed from the data set because as researchers we shouldn’t pick and choose which data points are include in results just because they don’t appear to fit with the rest of the results. In support of this, research has found that when humans have a strong belief about something, we subconsciously seek out belief consistent information and discard information contradicting our beliefs (Festinger, 1957). This is likely to affect our decision to remove outliers; if a researcher has a strong belief in their hypothesis (which is most likely) they may subconsciously remove data that disagrees with their hypothesis because they see them as outliers. In this case, removing outliers would be for the researcher’s personal gain i.e. a false significant result and a published research paper rather trying to finding a true significant result.
In conclusion, the researchers must use their discretion when deciding whether to remove outliers from their data. In my opinion the removal of outliers from data isn’t dishonest; outliers which are caused by anything but chance should be removed from the data set. However, because the removal of outliers is a subjective process, researchers should discuss the anomaly in the discussion section of their research project and justify why they have removed the outlier(s). This will prevent data being removed without just cause e.g. to enable researchers to prove their hypothesis. http://psychab.wordpress.com/2011/10/28/27/
Malcolm Gladwell made the topic trendy but outliers have been the bane of a statistical analyst’s existence all along. An outlier is essentially a number so far from the average (mean) that it seems out of place. In fantasy football we’re talking about statistical outputs that stand out from a player’s typical production.
For example, Doug Martin‘s 272 total yard, four touchdown performance in week nine against the Raiders; or for that matter his 33.4 fantasy point output the week prior. Anyone that was watching the game was blown away by Martin’s speed, vision, and Oakland’s tackling inefficiency. However, when you look at the numbers things just don’t add up. These outliers are performances that are hard to predict, and while Martin’s 50+ points in week nine was likely enough to win your weekly matchup, no one was predicting it and an argument can be made that it shouldn’t be considered when looking at his fantasy value for 2013. As such, it’s worth removing outliers when considering running back draft strategy overall.
Martin finished just ahead of Arian Foster in overall fantasy scoring last season as the #2 Running Back – but without his two standout efforts, he wouldn’t have been close. Foster was more or less steady – he had no monster games and very few underwhelming efforts either (except his 0.9 point effort in your fantasy championship week). Arguably, and without considering any other contextual factors, that makes Foster a better play. The big weeks are nice, but steady week to week output is really what you’re looking for from your RB1.
Weekly point outputs of 3, 5, 50, 6, 6 likely gets you a win in one week but puts you behind your opponents RB1 in four other contests. The average here is 14 points per contest. On the flip side, a back who scored 14 points week in and week out is dependable and is a weekly must start.
With that in mind, I took our top 12 consensus ranked running backs and removed any output that was more than ten points greater than their season average (replacing that number in the adjusted formula with their per game average number). I also tallied their ‘duds’ – games in which they scored fewer than six fantasy points.
The full data is here (Excel), do with it what you will (and, please feel free to share your comments below). My analysis follows below. It’s worth noting that unless a player was explicitly underused in week 17 those numbers were factored into the calculations.
So there you have it – none of this is a reason to take a player off your draft board and if you anchor the position with a back who has a high floor from week-to-week then perhaps a player like Martin with clear week-to-week homerun potential becomes more appealing. Still, you can’t bank on the big weeks. In my running back draft strategy though I’m all about ensuring a safe floor with the early picks and that’s why Arian Foster remains my number two running back as opposed to the trendier picks in Charles and Martin. http://lockerroomfantasysports.com/running-back-draft-strategy-controlling-for-outliers-when-assessing-value/
- If you watched Adrian Peterson last season you’d probably come away thinking that anything is possible and that even his outliers could be considered repeatable… still even when controlling for two 31+ point outputs Peterson’s per game average is still the best in the league.
- As mentioned above, Foster takes the edge over Martin when you control for Arian’s 0 outlier performances and Martin’s two big ones. Martin was still the 6th most effective back on this list when we took more than 40 points off his totals so there is still plenty to like, but with just the one poorly timed dud Foster’s season was probably more useful to his fantasy owners (though given his later ADP Martin’s had more value). Foster was an incredibly steady back, posting less than 8.5 points just once.
- It’s hard to hold it against him that he was part of Kansas City’s offense and he was employed erratically early in the season without sound explanation, but I’ll admit that this exercise made my reconsider my rank on Jamaal Charles. He posted three duds and is the third lowest per game scorer on this list when controlling for his 30+ point game against the Saints.
- On the flip side of that conversation, it’s nice to have a reminder of the value of Ray Rice. He posted two duds (5 and 4 point games) against tough opponents but was more or less matchup proof. Maybe he does lose a couple of carries to Bernard Pierce this year, but he’s the third best on the list in controlled average and has been extremely consistent for years. If we’re drafting to avoid floor, Rice is as safe a pick as any and this exercise just adds weight to that notion.
- CJ Spiller, LeSean McCoy, Steven Jackson and Matt Forte‘s contexts have all changed sufficiently that these numbers are not overly relevant. The latter two had no outliers of concern, anyhow. Nor did McCoy, though his numbers are skewed a bit by missing time to injury last season. Spiller’s first two weeks ended up being his best and his next two were his worst; beyond that he was remarkably consistent with just one week below 10 fantasy points from week five forward.
- Marshawn Lynch lost one point per game from his average when accounting for a huge week 17, but otherwise was a value to his owners week in and out while posting just two weeks below nine fantasy points. His value is tied to crossing the chalk, but he does so more often than not.
- Lastly, there are two more second year backs on our list. Alfred Morris is everyone’s darling, but our Mike Omelan warned against him as a bust candidate (relative to ADP at least). His 39.2 fantasy point effort in a playoff clinching game for the Redskins is an anomalous number. Controlling for this output costs Morris 1.5 points on his per game average and yet still his 13.95 ppg average is good for fourth best among the group. Plus he posted just one dud, missing the threshold by 0.1 points. Certainly last year’s production is nothing to cause anyone to shy away. Trent Richardson ranks as more of a risk when considering last year’s numbers, he had three games under six fantasy points and when controlling for his 2TD outlier in just his second career game he moves down a notch from the 6th to 7th highest back on the list. Still, when considering his injury issues and offensive changes he stands to improve on those numbers.
Last edited by a moderator:
