Community Commerce: Facilitating Trust in Mom-to-MomSale Groups on FacebookCarol MoserUniversity of MichiganAnn Arbor, MI, [email protected] ResnickUniversity of MichiganAnn Arbor, MI, [email protected] are turning to Facebook Groups to buy and sellwith strangers in their local communities. This trend iscounter-intuitive given Facebook’s lack of conventionale-commerce features, such as sophisticated search enginesand reputation systems. We interviewed 18 members of twoMom-to-Mom Facebook sale groups. Despite a lack ofcommerce tools, members perceived sale groups as aneasy-to-use way to quickly and conveniently buy and sell.Most important to members was that the groups felt safe andtrustworthy. Drawing on these insights, we contribute anovel framing, community commerce, which explains thetrust mechanisms that enable transactions between strangersin some groups. Community commerce fosters trust through(a) exclusive membership to a closed group, (b) regulationand sanctioning of behavior at the admin, member, and grouplevel, and (c) a shared group identity or perceived similarity(though, surprisingly, not through social bonding). Wediscuss how community commerce affords unique andsometimes superior trust assurances and propose designimplications for platforms hoping to foster trust betweenmembers who buy, sell, or share amongst themselves.Author KeywordsConsumer-to-consumer; e-commerce; online communities;community commerce; trust; FacebookACM Classification KeywordsH.5.m. Information interfaces and presentation (e.g., HCI):Miscellaneous;INTRODUCTIONFor over 20 years, a cornerstone of eBay’s success has beenthe feedback and reputation system that enables trustbetween buyers and sellers [16,35,59]. More recently, thatsame kind of reputation system-based trust undergirds manysharing economy applications. Platforms like Airbnb, Uber,TaskRabbit, and Upwork all rely on reputation systems toPermission to make digital or hard copies of all or part of this work for personal orclassroom use is granted without fee provided that copies are not made or distributedfor profit or commercial advantage and that copies bear this notice and the fullcitation on the first page. Copyrights for components of this work owned by othersthan the author(s) must be honored. Abstracting with credit is permitted. To copyotherwise, or republish, to post on servers or to redistribute to lists, requires priorspecific permission and/or a fee. Request permissions from [email protected] 2017, May 06 - 11, 2017, Denver, CO, USACopyright is held by the owner/author(s). Publication rights licensed to ACM.ACM 978-1-4503-4655-9/17/05 15.00DOI: SchoenebeckUniversity of MichiganAnn Arbor, MI, [email protected] trust, to enable the exchange of goods and servicesamong strangers [75]. From these successes, intuition wouldsuggest that consumer-to-consumer (C2C) transactionsonline could not succeed without the ability to vet and reviewbuyers and sellers.In this paper, we investigate why buying and selling on someFacebook sale groups seems to succeed despite the lack oftraditional e-commerce tools. Facebook sale group featureswere launched in 2015 to support closed groups ofindividuals from the same geographic area who buy, sell, andtrade goods among themselves [55]. However, Facebooksale groups do not offer standard C2C e-commerce featuressuch as sophisticated product search engines and filtering.E-commerce trust assurances are also noticeably absent fromthe platform—Facebook does not offer feedback orreputation systems, conflict resolution systems, frauddetection, escrow payment services, or consumer protectionprograms that offer money-back guarantees for failedtransactions.We focus on how trust—a necessary mechanism ine-commerce—can be established despite this lack oftraditional e-commerce assurances. We conducted semistructured interviews with 18 members of two activeMom-to-Mom (M2M) Facebook sale groups based in thesuburbs of a large Midwestern city. M2M sale groups, madeup primarily of mothers who buy and sell gently-usedchildren’s clothing and toys, were chosen for study becausethey are one of the most common and publicized types of salegroups on Facebook [1,4,30,84] and because they build onoffline traditions like rummage sales and church swaps.We found that members liked transacting through M2M salegroups because they were perceived as an easy-to-use way toquickly and conveniently buy and sell. Most important tomembers, however, was that the groups felt safe andtrustworthy. Indeed, members perceived M2M sale groupsas safer than other, more established, platforms such as eBayand Craigslist. We contribute a novel framing, which we callcommunity commerce, to explain the trust mechanismsenabling transactions between members of these M2M salegroups, absent traditional e-commerce assurances. For thesegroups, community commerce fosters trust between buyersand sellers through (a) exclusive membership to a closedgroup, (b) the regulation and sanctioning of behavior at theadmin, member, and group level, and (c) a shared groupidentity or perceived similarity based on commonalities such

as life-stage and geographic location. Perhaps surprisingly,social bonding and relationship building is not necessary forcommunity commerce to build trust and was not commonamong the people we interviewed.We discuss how community commerce can afford membersunique and sometimes superior trust assurances incomparison to traditional C2C e-commerce tools. We arguethat in community commerce, successful, sustainedmembership is perceived as a strong signal of an individual’strustworthiness. Further, we argue that membership is moredifficult to fake or manipulate, making it a more warranted[69] signal of trust than reputation system ratings. Thesefindings may inform other platforms aiming to foster trustbetween transacting members, though we also identifycontexts where the community commerce model may notapply. We also discuss the potential risks for discriminationwhen a centralized admin decides who is and who is nottrustworthy enough to join a group. We conclude with aproposal for how a large C2C platform, such as eBay, canimplement community commerce among its own members.RELATED WORKCommerce Requires TrustTransactions between buyers and sellers necessarily involverisk. In traditional commerce (see Table 1 for definitions),consumers perceive risks associated with financial loss andproduct performance [32], product safety [32,68], and timeloss [68]. E-commerce presents additional risks. Since theearly days of business-to-consumer (B2C) e-commerce inthe 1990’s, online shoppers have worried about beingdeceived by inaccurate product descriptions or fraudulentsellers, not being able to physically inspect products, notbeing able to easily contact customer service, and becomingvictim to privacy or payment security issues [50]. As such,consumers are more likely to shop online for productsperceived as low in purchase risk [44]. More recent researchhas demonstrated that online shoppers continue to worryabout product performance, financial loss, time loss, andfeelings of general disappointment with their purchase [29].The risks presented by online shopping explain the necessityof establishing trust between buyers and sellers online. Trustin an e-commerce context has been defined as a set of beliefsregarding the seller’s (a) integrity or honesty, (b) ability orcompetence, and (c) benevolence or general goodwill towardthe buyer [27]. These dimensions work to create a feeling ofconfidence that the other party can be trusted [27]. Trust inan online vendor predicts intent to use that online vendor[2,27,54], as well as actual frequency of use [54]. Whendeciding whether to use an online vendor, trust has beenshown to be as influential as the perceived usability of thevendor’s website [2,27,54].Trust in Consumer-to-Consumer E-CommerceUnlike B2C e-commerce, C2C e-commerce involves buyingand selling directly between individuals. Brokered C2Ce-commerce can take place on auction sites, such as eBay,TraditionalcommerceBrick and mortar, business-to-consumer(Barnes & Nobel)B2Ce-commerceOnline, business-to-consumer(Amazon)C2C e-commerceOnline, consumer-to-consumer Brokered Unbrokered3rd party broker (eBay)No 3rd party broker (Craigslist)Table 1. Definition of business models.while unbrokered C2C can take place on discussion forums,online communities, email groups, and online classifiedlistings, such as Craigslist [14,46]. In addition to the risksassociated with online shopping, C2C e-commerce poses itsown unique concerns. C2C auction sites, such as eBay, havebeen vulnerable to fraudulent bid activity designed to driveup auction prices [10]. Online classifieds sites, such asCraigslist, have been used to sell illegal, stolen, and recalledproducts [6,13,53], to run advance-payment scams [26,76],and, though very rarely, to commit violent crimes againstunsuspecting buyers [53].Several factors have been shown to influence buyers’ trust inC2C e-commerce generally, including perceived websitequality, third-party seals of approval, and the fear ofinformation asymmetry favoring the seller [33,34]. Researchon C2C commerce through USENET newsgroups andauction sites revealed that buyers’ most important criteria forselecting sellers were price and the trustworthiness of theseller, where the seller’s reputation was the most importantfactor in determining their trustworthiness [74]. In arandomized field experiment on eBay, sellers withestablished reputations had a higher probability of sale onmatched items, and higher prices [61]. However, attitudesspecifically about buying and selling differ. Trust and lowperceived risk with sellers correlate with more positiveattitudes about buying through C2C [45]. On the other hand,attitudes about selling are not influenced by the perceivedrisks posed by buyers (i.e., sellers generally don’t worry thatbuyers won’t pay) [45].Trust in a C2C platform also predicts higher user satisfaction[47], while mutual trust among users can positively influencetrust and loyalty in the actual platform [9]. In the case ofbrokered C2C, some have argued that buyers, sellers, and thecorporation (e.g., eBay) comprise a “community (ofcommerce),” which creates an expectation for ethicalbehavior and therefore enhances trust [8]. Other workinvestigating platform preference (eBay or Craigslist)revealed that consumers felt eBay’s institutionalassurances—such as their consumer protection policies—made the platform feel safer, while Craigslist’s face-to-facetransactions raised safety concerns [52].Designing for TrustThe HCI community has long been concerned with designingfor trust in e-commerce [12,19,51,66]. Trust is considered animportant component of the consumer’s user experience

[72]. Prior work has explored how online vendors signal trustto consumers [65], how the use of photography can affect anonline vendor’s perceived trustworthiness [63,64,73], andhow to best measure an online shop’s trustworthiness [67].Designing for trust in C2C platforms has focused more onreputation systems, designed to help the user identifytrustworthy parties, to incentivize good behavior, and todeter bad actors [35,59]. Other work has framed theeffectiveness of reputation systems within warranting theory,where cues that are more difficult for sellers to manipulate,such as feedback scores, are perceived as more informativeand trustworthy [69]. However, reputation systems are notperfect; feedback is often the product of reciprocation and/orretaliation between buyers and sellers [60], feedback can bemanipulated by sellers to boost their ratings [36,70], andreviews are sometimes copied across many sellers [15].Trust is also important in the design of platforms that supportC2C sharing [39,48]. For example, in the sharing economy,establishing trust is essential for face-to-face interactionsbetween strangers in someone’s home or car [7]. Prior workexplored how Airbnb’s design features can help reduceuncertainty and enhance trust between hosts and guests[21,40]. Robust reputation systems have also been shown tofoster reciprocity and trust between members of a sharingeconomy community [43]. Other work has shown thatperceived dissimilarity between members of a single-parentsgroup on a local sharing economy platform inhibited trustand participation in the group [41].Prior work has yet to investigate an emerging form ofunbrokered C2C e-commerce—groups of individuals whobuy and sell amongst themselves through social mediaplatforms, such as Facebook sale groups. While producttransactions have taken place since early Internet adoptionon sites like Usenet and the WELL [62], the scale of thesetransactions has grown dramatically and is no longerconfined to early Internet adopters. The M2M contextstudied here offers insights into a particular demographic ofconsumers who have been heavily studied in marketingcontexts but not in C2C contexts. This research begins to fillthis gap.METHODWe conducted an interview study with members of twoM2M Facebook sale groups. Prior to recruiting, the firstauthor joined, observed, and participated in one of the groupsfor approximately 6 months, from August, 2015 to February,2016. Once interviews began, the lead author joined andobserved three additional groups (i.e., groups mentioned byinterviewees) for approximately 5 months (from FebruaryJune, 2016). During these periods of participant observation,the lead author regularly took notes of member interactions.This observational research informed the study’s interviewquestions as well as contributed to the overall understandingof how M2M sale groups work.We recruited participants by posting a message to twodifferent M2M Facebook sale groups (recruitment messageswere posted with the group admin’s permission). The twogroups selected were based in the suburbs of a largeMidwestern city and were selected because the groups wereactive with regular interaction between members and acritical mass of communication and members [38]. At thetime of the study, the two groups reported 3,715 members(with 1 admin) and 8,144 members (with 3 admins)respectively. The geographic territories of the two groups—as indicated by their official Facebook group names—substantially overlapped (sharing 4 out of 5 towns) andspanned approximately 18 miles between its farthest points.Those towns ranged in population from roughly 6,000 to95,000 residents, representing a total population ofapproximately 260,000. According to Census Bureaufigures, the population of these towns ranged between 72%to 94% white, with a median household income range fromapproximately 70K to 94K. More detailed informationabout the specific towns and groups is intentionally omittedin order to protect the privacy of participants.ProcedureWe conducted semi-structured interviews between Februaryand June 2016. Interviews lasted on average 53 minutes andranged from 39 to 65 minutes. We conducted interviews untilwe reached data saturation. In total we conducted 18interviews (1 via phone, 17 in-person) with 10 participantsfrom the first group and 8 participants from the second group.Participants were provided a copy of a consent form.Participants were first asked about their Facebook use (e.g.,when they joined the site, the number of groups they belongto). Participants were then asked about how Mom-2-Momsale groups work and about any particular favorite (ordisliked) groups. Next, participants were asked to describetheir experiences buying and selling products through M2Msale groups. Finally, participants were asked how theirexperience with M2M sale groups compared to theirexperiences with other sites like eBay or Craigslist. Theinterviews concluded with a short paper-based demographicssurvey. Participants were compensated with a 25 gift card.The authors’ Institutional Review Board determined that thestudy was exempt.We audio recorded the interviews and then transcribed themusing a transcription service. We analyzed the transcriptsusing an inductive approach to identify themes and developcodes. The first author read through all transcripts to identifyhigh level themes. Then, four of the 18 transcripts werecoded with those themes in mind to develop a morecomprehensive list of 62 codes. A fifth interview transcriptwas then coded independently by two coders, who discussedand refined the codebook. Finally, a sixth interview wascoded independently by the same two coders with a resultinginter-rater reliability Fleiss Kappa of .71, demonstratingsufficient agreement between coders [24,42]. The full corpusof interview transcripts was coded using ATLAS.ti. The twocoders independently coded nine transcripts and thenreviewed the coding of the other nine transcripts.

All 18 participants were female and on average 35 years old(ranging from 27-53 years). The majority (56%) ofparticipants indicated that they worked outside of the home,while 33% were stay-at-home moms. All participants weremarried or living with a partner. One participantself-identified as black or African American; the restself-identified as white or Caucasian. As a result, this studyoversamples white Americans, which according to USCensus data only represent 62% of the US population [81].Participants also reported a higher household income thanthe national median household income of 55,775 [86]; 89%of participants reported a household income greater than 50K per year. See Table 2 for additional demographics.Participants were active Facebook users with a median of 9years on the platform (ranging from 5-13 years), averagingabout 368 Facebook friends. Participants indicated they weremembers of a median of 7 Facebook sale groups (rangingfrom 2-30 groups), with a median of 4 groups specificallybeing M2M sale groups (ranging from 1-20 groups). Twoparticipants identified themselves as both members andadmins of M2M sale groups. On average, participants weremembers of the M2M sale group (from which they wererecruited) for approximately 14 months but membershipranged from 2 to 24 months.How Facebook Sale Groups WorkWe begin with a general description of how Facebook salegroups work, based on both group observation and interviewdata. Facebook Groups launched in 2004 to provide a privatespace for small groups of friends to interact [22]. Elevenyears later, one of the most common types of Groups onFacebook are “buy, sell, trade” groups [55] (also known as“sale groups”). Sale group members typically live in thesame geographic area. The groups are managed by one orseveral volunteer admins and their product focus can varyfrom generic “online garage sale” groups to “guy stuff”groups and “antiques/collectibles” sale groups. In 2015,Facebook launched features for creating sale posts andflagging products as “sold” or “available” [55]. As of 2016,Facebook does not offer common C2C e-commerce tools,such as a sophisticated product search engine, reputation andfeedback systems, or consumer protection policies.In order to participate in most Facebook sale groups,members must request to join; group admins determine whocan and cannot join. Members can participate as both buyersand sellers (for clarity, we refer to members as buyers whenthey are describing their experiences buying and vice versafor sellers/selling). The selling process begins by creating asale post with a price, photo, and description of the product.Facebook provides a standard sale post form for groups setto “buy, sell, trade”. Otherwise, sale posts are created usingdiscussion posts or, more rarely, by posting to a group’sphoto albums, which represent product categories. Sellersuse a variety of acronyms in their sale posts (see Table 3).Sales posts are typically tagged as “PPU” (Porch Pickup),meaning the seller will leave the product on their front porchEducationHouseholdIncomeHigh SchoolAssociates/TradeBachelor’sMaster’s or above 25K 25-49K 50-74K 75-99K 100- 149K 150KParticipants(N 9%11%22%23%17%12%14%12%Table 2. Additional participant demographics and USCensus data for education [83] and income [84].to be picked up by the buyer, who will leave payment underthe door mat. It is less common for members to meetface-to-face, though exceptions are made for larger or moreexpensive products.New sale posts are either pushed to a buyer’s phone(depending on a user’s Facebook settings) and/or aredisplayed within a buyer’s Facebook News Feed. Sale postsare also visible on the Facebook Group’s main page, thoughbuyers reported rarely visiting the page directly. Buyers alsoreported that they rarely used the Facebook Group’s searchbar to look for products. When a buyer wants to purchase aproduct, they comment on the sale post with “int” or“interested.” This creates a soft agreement between the buyerand seller. Group members indicated a strong norm thatsellers will sell to the first buyer who responds. Bidding(above the advertised price) is not allowed, nor is arrangingsales through private messaging. Buyers and sellers useFacebook Instant Messenger to address product questions, toarrange a pick-up time, and to share the seller’s address.Once these details are confirmed, sellers typically commenton the sale post that the sale is “pending” or “pending pickup.” Occasionally, a buyer will change their mind afterlearning more about the product through private message, inwhich case the seller will proceed to the next buyer whoresponded or will comment “available” to solicit newpotential buyers.Members indicated several motivations for participating inM2M sale groups. Buyers were mainly interested in findinggood deals on gently used children’s gear. Sellers weremainly motivated to declutter their homes and recoup someof the money originally spent on their children’s items. Themoney earned selling was commonly used to purchase itemsfrom other members. Some members cited sustainabilitymotivations for buying and selling used goods.RESULTSWe first describe the perceived risks of using M2M salegroups, followed by a description of the platform featuresthat were most salient to participants. We then report onthemes of safety and trust, as well as comparisons made toother C2C platforms like eBay and Craigslist.

Perceived Risks of Facebook Sale GroupsBuyers commonly mentioned that products might not be “asdescribed”; for example, items described in a sale post asbeing in GUC (“good, used condition”) may have rips orstains. This was especially concerning for buyers given thestrong group norm against haggling or changing your mindonce a pick-up has been arranged (even if disappointed afterphysically inspecting the product). While there areexceptions to this practice (buyers can walk away from aproduct that was blatantly misrepresented by the seller), thegroup norm for completing transactions is so strong thatsome members rarely even inspect the product when pickingit up, “I don’t actually even look at the item when I get there.I put it in the car, leave my money, and go home” (G).For sellers, theft was one of the most commonly mentionedrisks. Sellers worried about unscrupulous buyers takingproducts without payment, leaving only partial payment, ortaking cash left by previous buyers. Some sellers hadstrategies for mitigating these risks when selling pricieritems, such as arranging to meet the buyer at a publiclocation; however, face-to-face meetings were described asrare by both sellers and buyers. Sellers also complainedabout the risk of “no-shows,” when a buyer does not showup to pick up and pay for a product. Sellers often included“no holds” in the language of their sale posts because theyperceived a greater risk of a no-show if the pick-up did notoccur immediately.Members were also aware of the risk of being “scammed” onthe group. M2M sale groups sometimes get requests fromstruggling mothers who are looking for free diapers, formula,or other products. However, some requests come from “fake”members who join to solicit donations with a dishonest storyof hardship or tragedy. Sometimes, members discovered thattheir donated goods were not actually needed if they wereimmediately posted for sale on another group or site;“People put the post out that they’re in need of something. ‘Ihave a seven week old newborn coming, baby came early,’and then they sell it on other sites for profit” (J).Members also spoke to potential but non-specific safetyrisks. For example, members acknowledged that sharingtheir address with buyers could be risky, “I sometimes thinkthat’s a little bit dangerous 'cause I sometimes don’t wantpeople to know where I live” (B). Other members avoideddoing any pickups after dark; one member occasionallyasked her husband to accompany her to a pickup in a lessfamiliar neighborhood. One African American memberdescribed the risks she associated with doing porch pick-upsin predominately white neighborhoods, despite being aresident of a similar, neighboring community. She explained,“That nervousness is always there when I roll up onsomeone’s home and I’m walking to the porch and grabbingsomething off a porch. Like, waiting for the police to come”(J). We return to this in the OTISOFCFSInterested (in product)Porch PickupSale is pending pickupSale fell through, product availablePosted On Other Sites (or sale groups)Excellent/Good Used ConditionNew With/Without TagsIn Search Of (looking to buy)First Come First ServeTable 3. Common terms used on M2M sale groups.Features of Facebook Sale GroupsSale groups are easy and convenientBuyers described M2M groups as an easy and convenientway to shop because buyers can shop from their phone attimes that are convenient for them. Some buyers mentionedthat they regularly used Facebook, which also made salegroups convenient. Buyers also liked not needing tophysically sift through many products at a store or garagesale. “Instead of it getting delivered to your mailbox like apackage would, you just drive to the porch, which if you’resmart, you can do it on your way grocery shopping You canput it into your day where you’ll just swing by, jump out ofthe car, grab it, you’re good to go” (F). As such, buyers’favorite M2M groups were those located within a short driveof their home. Other buyers appreciated how products arepushed to their phones and News Feeds without the effort ofa product search or having to check the group’s homepage:“This is nice 'cause it just kinda pops up a whole bunch ofdifferent things you might not even know you want until yousee it” (H). However, two members reported that the numberof sale posts in their feeds could at times feel overwhelming.Other members mentioned that the group was not useful forfinding specific products that they needed right away, suchas specific sized clothing for a child.Selling was also described as easy and convenient. Theselling process was commonly described as requiring three“easy” steps: create a sale post, schedule a pick-up, and leavethe product on the porch; for example, “I just took a pictureof six pairs of shorts that my son won’t wear I took apicture and I made twenty dollars. It took five minutes to doit. I put it on the porch, they picked it up, and it’s done” (N).Sellers felt that selling items through garage sales,consignment shops, or church swaps required more effortand time, and did not easily allow for selling a single item orsmall batches of items at a time. Selling on eBay was alsodescribed as requiring more work, especially in terms ofpackaging and shipping items, or as one participantexplained, “Who wants to go to the post office every day?”(I). Sellers also appreciated that Facebook is free, unlike siteslike eBay that charge listing and/or service fees.Sale groups are speedySellers noted that they often receive responses to their saleposts within minutes of posting. In contrast, sellers felt that

it takes longer to receive responses on Craigslist, whichcould take several days or weeks. Some members alsoobserved that, unlike Craigslist’s e-mail-based system,Facebook’s instant messaging feature facilitates speedy andefficient communication between buyers and sellers, “Themom-to-mom thing seems to be a little more quick inresponse, like Craigslist you have to wait for an email. So ifsomebody isn’t checking their email every day or every hour,you might wait a week to hear back from them, and then tofind out that the thing’s been sold” (H).Buyers also preferred M2M groups because, unlike on eBay,they do not have to wait for their purchase to ship—they cantypically pick it up the same day. Some buyers alsomentioned that they dislike paying for shipping on eBay.Both buyers and sellers mentioned avoiding eBay because ofthe auction/bidding system which they perceived as morework, more confusing, and requiring more time fortransactions to close. In contrast, sale group members likedknowing right away that they “won” the product (i.e.,because they were the first buyer to respond).Sale groups are effective for buying and sellingBoth buyers and sellers preferred more active M2Mgroups—those with many sale posts daily. Buyersappreciated the constant stream of new products. Sellersvalued quick responses and appreciated selling to a clearlydefined target audience, “It’s your target audience. If I’mselling kids’ stuff, I’m gonna go to a mom-to-mom sale site,'cause it’s easier” (E).Despite generally describing sale groups as effective, bothbuyers and sellers noted some disadvantages. Buyers werepleased with the number of new products offered daily butwere sometimes frustrated with the competition betweenbuyers to be the first to respond. “You see something, andyou’re like, "Oh my gosh, this is great," and there’s 10people who say they’re interested and you know it’s nevergoing to get to you. That can be frustrating” (O).Sellers who were usually able to sell items quickly wereconfused w

Craigslist, have been used to sell illegal, stolen, and recalled products [6,13,53], to run advance-payment scams [26,76], and, though very rarely, to commit violent crimes against unsuspecting buyers [53]. Several factors have been shown to influence buyers’ trust