Knowing me, knowing you'-using profiles and social networking to improve recommender systems profile 1 profile 2 file 5 rofile 3 iliat similar profile similar profile dissimilar profile similar profile high rating overlap high rating overla high rating overlap low rating overlap profile 4 profile 6 profile 8 profile 7 unfamiliar unfamiliar similar profile dissimilar profile dissimilar profile dissimilar profile low rating overlap high rating overlap low rating overlap low rating overlap Fig 6 Chosen profiles with ratios and characteristics familiarity conditions similarity conditions rating overlap conditions profile 1 profile 1 5575%|vs44.25% 58375%V1625% 15.5% unfamiliar dissimilar high rating overlap profile 7 6875%6512.5% 88.5% 1.5 familiar dissimilar high rating overlap low rating overlap 35675%s43.25% 784.75%s15.25% 11855% 14.5% familiar unfamiliar similar dissimilar high rating overlap low rating overlap 48 875%vs51.25% 8 75%|vs 525% 815%vs 18:5% familiar dissimilar igh rating overlap Fig 7 Profiles chosen- individual percentages per condition · Familiarity 3.2.7 Choice confidence In this experiment familiarity did not prove to be a For every choice, participants provided a confidence significant influence on participants'choices. rating on a Likert scale from 1 to 5. We considered a Overall only condition 3 turned out to be significant deviation of the mean from 3(p <0.05)as statistically significant examinable. With the exception of condition 10, rating means significantly deviated from 3 (see Fig 8) · Profile similarity Profile similarity had a significant impact on the. Familiarity conditions recommender choice he only condition where participants were Rating overlap confident in their choices was condition 1. where Rating overlap also had a significant impact on the the choice was between a familiar and unfamiliar recommender choice. Thus participants generally recommender that was similar and had high rating chose films from recommenders with whom they had a high rating overlap Examining the different visualisations of rating overlap, text and symbol, it Profile similarity conditions is worth noting that there was a higher tendency to In those conditions it was interesting to observe choose films from recommenders with high rating that participants were more confident in their overlap in the symbol conditions (87.6 %)rather choices in conditions 5 and 7 where recommenders than in the text conditions(82.5 %) had a high rating over lap than in conditions 6 and BT Technology Journal.Vol 24 No 3. July 2006‘Knowing me, knowing you’ — using profiles and social networking to improve recommender systems BT Technology Journal • Vol 24 No 3 • July 2006 93 • Familiarity In this experiment familiarity did not prove to be a significant influence on participants’ choices. Overall only condition 3 turned out to be statistically significant. • Profile similarity Profile similarity had a significant impact on the recommender choice. • Rating overlap Rating overlap also had a significant impact on the recommender choice. Thus participants generally chose films from recommenders with whom they had a high rating overlap. Examining the different visualisations of rating overlap, text and symbol, it is worth noting that there was a higher tendency to choose films from recommenders with high rating overlap in the symbol conditions (87.6 %) rather than in the text conditions (82.5 %). 3.2.7 Choice confidence For every choice, participants provided a confidence rating on a Likert scale from 1 to 5. We considered a significant deviation of the mean from 3 (p <0.05) as examinable. With the exception of condition 10, all rating means significantly deviated from 3 (see Fig 8). • Familiarity conditions The only condition where participants were confident in their choices was condition 1, where the choice was between a familiar and unfamiliar recommender that was similar and had high rating overlap with the participant. • Profile similarity conditions In those conditions it was interesting to observe that participants were more confident in their choices in conditions 5 and 7 where recommenders had a high rating overlap, than in conditions 6 and Fig 6 Chosen profiles with ratios and characteristics. Fig 7 Profiles chosen — individual percentages per condition. profile 1 familiar similar profile high rating overlap profile 2 unfamiliar similar profile high rating overlap profile 5 familiar dissimilar profile high rating overlap profile 3 familiar similar profile low rating overlap profile 4 unfamiliar similar profile low rating overlap profile 6 unfamiliar dissimilar profile high rating overlap profile 8 unfamiliar dissimilar profile low rating overlap profile 7 familiar dissimilar profile low rating overlap profile 1 55.75% familiar profile 2 44.25% unfamiliar profile 3 50% familiar profile 5 56.75% familiar profile 7 48.75% familiar profile 4 50% unfamiliar profile 6 43.25% unfamiliar profile 8 51.25% unfamiliar profile 1 83.75% similar profile 5 16.25% dissimilar profile 3 87.5% similar profile 2 84.75% similar profile 4 84.75% similar profile 7 12.5% dissimilar profile 6 15.25% dissimilar profile 8 15.25% dissimilar profile 1 84.5% high rating overlap profile 3 15.5% low rating overlap profile 5 88.5% high rating overlap profile 2 85.5% high rating overlap profile 6 81.5% high rating overlap profile 7 11.5% low rating overlap profile 4 14.5% low rating overlap profile 8 18.5% low rating overlap vs vs vs vs vs vs vs vs vs vs vs vs 1 2 3 4 5 6 7 8 9 10 11 12 familiarity conditions similarity conditions rating overlap conditions