Some papers test network hypotheses by constructing interaction networks between users or communities, sometimes over time. Data gaps also represent a high risk to these papers, since missing submissions may result in unobserved ties in the network. Tan and Lee observe histories of user accounts participating in different communities, while Fire and Guestrin observe network ties over time modeled on user histories. Substantial blocks of missing data, including the potentially large amount of missing submissions from Reddit's nascency could redraw the map of community ties on the platform. The average user in this sample commented 6.8 times and commented 96.6 times from late January 2006 through February 2016. These averages occur on a highly skewed distribution, as illustrated by the log-histograms in Fig 1.
The issue has a compounding effect, since a small number of users create a large amount of the content on the platform. The more posts and comments someone produces, all else being equal, the more likely their histories will be affected by the missing data issue. As we have also shown, unknown unknowns expanded dramatically in the 16 months following February 2016 and now include 36 million missing comments and 28 million missing submissions. We also considered the degree to which missing content differentially affects individual subreddits. If data from some communities were more affected by gaps than others, the gaps could influence the results of comparative research about populations communities .
If gaps affected communities equally, we would expect that the number of missing pieces of content monotonically rises with the number of overall pieces of content posted to a subreddit. As Fig 5 shows, we find only marginal evidence for such a supposition. While more missing content is positively and significantly associated with larger subreddits, we do not find a direct relationship. One confounding factor may be the temporal "center of gravity" of a subreddit—older subreddits are positioned at a time when more content was missing, on average, which may differentially affect older subreddits. The time at which a subreddit was created, however, is a poor proxy for the true "center of gravity" of content (i.e. the time at which a subreddit was most active), a characteristic that these models do not account for.
Other papers test hypotheses based on participation sums within communities. Gaps that are biased toward particular communities will represent a risk to the validity of these studies. Matias observes levels of subreddit participation by moderators, observes relative participation levels of subreddit commenters in other subreddits, and observes moderator participation in "metareddits". Barthel observes comments about political candidates across Reddit during a period where many submissions are within the dataset. Barbaresi analyzes German language text to identify relative commenting rates about places in Germany.
Horne and Adali consider posts within /r/worldnews to determine linguistic characteristics of why some news frames are more visible than others. Dosono et al considers a specific set of communities associated with self-expression of Asian-American Pacific Islander identity on the platform. We prefer the Cultiver sheets for their softness, slightly lower price, and color options, but if you want more texture to your linen we recommend Rough Linen Sheets. These were the roughest of the seven sets we slept on, but that texture isn't unpleasant (it's about as prickly as a kitten's tongue).
We have read durability complaints about these sheets, but the problem doesn't seem pervasive. Like Cultiver, Rough Linen sells its sheets by the piece, so you could slowly invest in a set, or just buy a top sheet and pillowcase to use with a durable fitted cotton sheet. As we showed in Fig 5, gaps do not appear to be evenly distributed across communities, since the number of missing comments and submissions per community is not strongly correlated to the number of observed comments and submissions in that community. User history analysis papers face the highest risks from missing data, since a missing comment or submission could hide an important part of that user's history. A network analysis may fail to include a user's participation in a particular community or interaction with a key user.
Furthermore, survival analyses might mis-estimate the moment of a person's departure or their participation level. Network analysis papers also face high risks, since the presence or absence of a tie could be dependent on the missing data. Sum analyses that count the size or incidence rate of participation in subreddits or the use of certain kinds of language face moderate risk, especially when analyzing small communities and rare events. Content analysis that involves training machine learning systems on Reddit comments face minimal risk because their research rarely includes claims about the population of Reddit users. Missing comment IDs could be attributed to many possible causes.
A major point of evidence in this direction is that during the Reddit blackout , the number of missing comments and submissions spiked significantly. In this case, due to the constraints of the platform, it is not possible to disambiguate private content from truly missing content—lookups on private IDs appear to yield no data . As a social news platform, Reddit hosts discussions about text posts and web links across hundreds of communities called "subreddits" .
Discussions from public subreddits are aggregated by a variety of news aggregators to create the "front page of the web" that Reddit was founded to provide to its readers . The Baumgartner dataset follows this common experience and includes submissions and comments. On July 2, Reddit began experiencing a series of blackouts as moderators set popular subreddit communities to private, in an event dubbed "AMAgeddon", a portmanteau of AMA ("ask me anything") and Armageddon. This was done in protest of the recent firing of Victoria Taylor, an administrator who helped organize citizen-led interviews with famous people on the popular AMA subreddit.
Organizers of the blackout also expressed resentment about the recent severance of the communication between Reddit and the moderators of subreddits. The blackout intensified on July 3 when former community manager David Croach gave an AMA about being fired. Before deleting his posts, he stated that Ellen Pao dismissed him with one year of health coverage when he had cancer and did not recover quickly enough.
Following this, a Change.org petition to remove Pao as CEO of Reddit Inc. reached over 200,000 signatures. Pao posted a response on July 3 as well as an extended version of it on July 6 in which she apologized for bad communication and not delivering on promises. She also apologized on behalf of the other administrators and noted that problems already existed over the past several years. On July 10, Pao resigned as CEO and was replaced by former CEO and co-founder Steve Huffman. In practice, we observe 78 subreddits where at least 20% of the comments are missing, and 1,755 subreddits where at least 20% of the submissions are missing. Among subreddits that have any dangling references, on average they are missing at least 35% of their submissions.
The R2 score in a model predicting the volume of a community's missing observations from the volume of observed comments and submissions only explains 30% of the variance of missing comments and 10% of the variance of missing submissions . The risk to any specific study will depend on the distribution of gaps across the specific communities being compared. Papers that test hypotheses based on user histories on Reddit may have substantial gaps in the histories that they seek to test. Analyses on user histories that consider the history in full are, in general, exposed to the highest risk—analyses that are especially sensitive to high-volume users are very likely, on average, to consider users whose histories have gaps. Hessel et al , for example, observes and compares sums of comment participation between subreddits, and observes the full chain of user history—Hessel et al adopts a similar approach. Barbosa et al compares year cohorts of individual-level behavior across all of Reddit, and as has been shown, some years are more affected by gaps than others.
Additionally, the large number of potential missing submissions from Reddit's earliest years may also affect these findings. If a user history analysis requires the complete posting history between subreddits for a given user, gaps in such transmissions may constitute meaningful gaps in explaining a wide array of hypotheses. In this case, the "average" Redditor may be exposed to a total maximum risk level of ∝ 4.18% likelihood for missing at least one comment and ∝ 4.46% for missing at least one submission. In the 7,400 individual set, approximately 2% of the sampled users had a 50% or greater chance of having a missing comment, and 2.6% of the sampled users had a 50% or greater chance of having a missing submission. We offer these rough approximations to communicate a qualitative sense of how this missing data issue may create an appreciable problem for some forms of research. We include a more detailed typology of possible errors below.
Although once you have sensitive teeth it cannot be reversed, switching to a daily sensitivity toothpaste, like Sensodyne, can protect against the symptoms of sensitivity when used twice a day, every day. Sensodyne is specially formulated for tooth sensitivity relief and is the #1 dentist recommended toothpaste brand for sensitive teeth. As a network of communities, Reddit's core content consists of posts from its users. Users can comment on others' posts to continue the conversation. A key feature to Reddit is that users can cast positive or negative votes, called upvotes and downvotes respectively, for each post and comment on the site. The number of upvotes or downvotes determines the posts' visibility on the site, so the most popular content is displayed to the most people.
Users can also earn "karma" for their posts and comments, a status that reflects their standing within the community and their contributions to Reddit. Posts are automatically archived after six months, meaning they can no longer be commented or voted on. First RT currently very bad reviews 33% and definetly will drop more Also imdb currently 6 also will drop a lot more that always the case also user reviews mostly very terrible reviews . All datasets have biases, no matter how complete we wish them to be. In the process of designing research, conscientious researchers will study those biases, document them, and account for them as best as possible. In this paper, we have shown ways in which an influential public dataset does not represent the "complete" record that its publisher and users aspired to.
We have documented per-user risks of missing data, risks from the uneven distribution of missing data over time, and risks in the uneven distribution of missing data across communities. We have outlined the risks to research validity represented by these data gaps, including some of our own work. In some cases, it is possible that some of the missing IDs were never associated with any content. In correpondence, Baumgartner reported successfully retrieving many of the IDs not present in the original corpus, confirming that many of these missing IDS are genuinely associated with content.
In that event, we know the status of the object, and can confirm that it is not falsely "missing" from the dataset, but is instead truly missing in that it has been intentionally erased. As researchers use computational methods to study complex social behaviors at scale, the validity of this computational social science depends on the integrity of the data. On July 2, 2015, Jason Baumgartner published a dataset advertised to include "every publicly available Reddit comment" which was quickly shared on Bittorrent and the Internet Archive. This data quickly became the basis of many academic papers on topics including machine learning, social behavior, politics, breaking news, and hate speech. We have discovered substantial gaps and limitations in this dataset which may contribute to bias in the findings of that research. In this paper, we document the dataset, substantial missing observations in the dataset, and the risks to research validity from those gaps.
Sensodyne Rapid Relief Whitening toothpaste uses an active ingredient called stannous fluoride to build a protective barrier over exposed dentin, the inner layer of your teeth. At the first brush, it starts to form a shield that quickly blocks the tiny holes in the sensitive areas of your teeth. It also contains sodium tripolyphosphate, which gently lifts and helps prevent surface tooth stains from forming. Brushing twice a day, every day, provides clinically significant sensitivity relief in as little as 3 days and thereafter and whitens teeth. Sensodyne Rapid Relief toothpaste uses an active ingredient called stannous fluoride to build a protective barrier over exposed dentin, the inner layer of your teeth.
Brushing twice a day, every day, provides clinically significant sensitivity relief in as little as 3 days and thereafter, giving you the relief you want in the time you need it. Aggregate Reddit user data has been used for scientific research. For example, a 2014 study showed how subreddits can support role-based group recommendations or provide evaluation towards group stability and growth. Another study evoked a connection between cognitive and attention dynamics and the usage of online social peer production platforms, including the effects of deterioration of user performance. There is also work that has studied the influence of Reddit posts on the popularity of Wikipedia content.
As with many linen sheets, this set may have durability issues. After using the set three times, former Wirecutter editor-in-chief Jacqui Cheng found that the bottom sheet tore. Otherwise, she was happy with the top sheet and pillowcases for the year she long-term tested, and three of our staffers bought sets in summer 2018 and haven't had any durability complaints. We haven't seen other complaints for the West Elm set, and although West Elm and Pottery Barn don't feature customer reviews on their sites, we have seen good feedback about these sheets on Reddit. If you want a softer set of linen sheets, and price is no object, we recommend those from Bella Notte. At their price of $660 for a queen set at the time of testing, they may seem ridiculously expensive, but they were our testers' unanimous favorite.
The texture feels almost buttery compared with that of the Cultiver and Rough Linen sheets, and the fabric wrinkles less and has a springy quality that makes it drape more beautifully across the bed. Bella Notte also sells its sheets, which come in eight subdued colors, by the piece. The Cultiver sheets typically come in around 14 colors , which is the widest selection of any of our top contending sets. The colors are really pretty and offer a good balance of light and dark. If you want to look at the colors in person, you can order swatches. Cultiver's customer service rep told us the company can generally ship the swatches within three business days, although it can take up to three weeks, depending on your location.
(You'll also have to pay a $10 shipping charge.) The Cultiver set also has slightly nicer detailing than the Rough Linen set, with very clean mitered corners and thick hems along all the edges of the top sheet. Sensodyne Rapid Relief Whitening toothpaste is specially formulated to relieve tooth sensitivity pain in as little 3 days with twice daily brushing. Since it also contains sodium tripolyphosphate, you can expect to have whiter teeth over time, as it gently lifts and helps prevent surface tooth stains from forming. Use Sensodyne as your daily toothpaste, brushing twice a day, every day, for lasting tooth sensitivity relief. With Sensodyne, you can also get the benefits of fluoride, cavity protection, and fresh breath to help you maintain healthy and sensitivity-free teeth. Certain occupations may involve exposure to respiratory irritants or sensitisers; in which case, surveillance is indicated, with pre-employment and regular spirometry.
If accelerated lung function decline occurs, it is important to refer the worker to a specialist occupational clinic. If asthmatic symptoms occur , simple spirometric measurements should be performed 2-hourly from waking to going to bed, on days at work and away from work, for 4 weeks to assess any diagnostic patterns for occupational asthma . PEFs should be completed using specialised forms that allow the worker to write down their work times, wake and sleep times, jobs done during the day and treatment taken. These can be downloaded from Once the worker has performed the measurements, they can be inputted in a computer program, such as Oasys (Occupational Asthma System; freely available for download from ) [10–12] for analysis (fig. 5). When serial PEFs are of good quality, the mean pooled sensitivity for the diagnosis of occupational asthma is 82% and specificity is 89% . Some media outlets and political commentators also condemned the banning of the r/The_Donald and r/ChapoTrapHouse subreddits as a violation of the right to free political expression.
Registered members submit content to the site such as links, text posts, images, and videos, which are then voted up or down by other members. Submissions with more upvotes appear towards the top of their subreddit and, if they receive enough upvotes, ultimately on the site's front page. Although there are strict rules prohibiting harassment, it still occurs, and Reddit administrators moderate the communities and close or restrict them on occasion.
Moderation is also conducted by community-specific moderators, who are not considered Reddit employees. And of the 21 samples we initially tested in 2018—including from sets three to four times the price—the Pottery Barn and West Elm fabrics were among the softest and most pleasant against the skin. In our original 2016 linen sheet review, we featured the West Elm set as our main pick, and we still think they're very good for their relatively low price. Similar to other brands, Bella Notte does not offer a warranty and will accept returns of only unused, unwashed items within 30 days of receipt. The company no longer charges a restocking fee, but you may want to order swatches to make sure you like the fabric and color before ordering a set. We can't guarantee that Cultiver's sheets will last longer than those from other brands, but the fabric feels thicker and more substantial than the lighter sets from Pottery Barn and West Elm.
Wirecutter supervising editor Winnie Yang, who has owned linen sheets from multiple brands and experienced durability issues with almost all of them, said her Cultiver top sheet is the only one she's used that hasn't developed holes. She also has the coordinating duvet cover we recommend and says it gets a lot of abuse from her pets, but there are no holes, worn spots, or fraying. We also haven't seen complaints about thinning sheets in owner reviews (although we've also seen fewer owner reviews for Cultiver than for other brands). Invesco Mortgage Capital is a vastly different, and smaller, company than it was when it entered 2020. In February of 2020, the stock was four times higher than it is now. Since mortgage REITs generally trade based on book value per share and dividend yield, it will take years to build back up to those levels organically.
Invesco Mortgage is trading above its book value per share of $3.65 per share as of March 31, 2021. Overall, Figs 3 and 4 illustrate an initially erratic distribution of errors throughout the dataset. For researchers concerned about the dispersion of missing objects, consider the dark blue line which shows the cumulative percent of missing objects or the simple percent of missing content per month of data in the medium blue. For researchers concerned with the percent of missing content to date, consider the light blue line which charts how much content appears to be missing from the beginning of the corpus until the end of our current analysis.
These errors appear to occur directly within periods of substantial research interest and may affect several published results . While the rate of error was particularly erratic in early years, and the distribution of errors per ID gap continues to be erratic , the error rate per month has evened out to around 1% missing data per month. Yes, brushing too hard or too frequently can contribute to gum recession and/or enamel wear, which, over time, can expose the soft, inner layer of your tooth, known as dentin, and can lead to sensitive teeth. The ADA recommends that you brush for 2 minutes twice a day with a soft-bristled or electric toothbrush. Using Sensodyne toothpaste twice a day, every day, can help.
These 20 social media templates will save you a ton of time and effort, from creating content, to publishing posts and measuring results. For April Fools' Day 2015, a social experiment subreddit called r/thebutton appeared. User accounts created before that day were eligible to participate. A user could only click the button once, or opt not to click it. If a user clicked the button the timer was globally reset to 60 seconds, and the user's "flair" (an icon next to the user's name) changed color.
Colors were assigned based on a gradient from purple to red with purple signifying up to 60 seconds and red as low as 0 seconds. The countdown reached zero several times due to technical problems but eventually expired without further problems on June 5, 2015, after which the subreddit was archived. The website is known for its open nature and diverse user community that generate its content.
