Reliable online social network data collection

Large quantities of information are shared through online social networks, making them attractive sources of data for social network research. When studying the usage of online social networks, these data may not describe properly users’ behaviours. For instance, the data collected often include content shared by the users only, or content accessible to the researchers, hence obfuscating a large amount of data that would help understanding users’ behaviours and privacy concerns. Moreover, the data collection methods employed in experiments may also have an effect on data reliability when participants self-report inacurrate information or are observed while using a simulated application. Understanding the effects of these collection methods on data reliability is paramount for the study of social networks; for understanding user behaviour; for designing socially-aware applications and services; and for mining data collected from such social networks and applications. This chapter reviews previous research which has looked at social network data collection and user behaviour in these networks. We highlight shortcomings in the methods used in these studies, and introduce our own methodology and user study based on the Experience Sampling Method; we claim our methodology leads to the collection of more reliable data by capturing both those data which are shared and not shared. We conclude with suggestions for collecting and mining data from online social networks.Postprin

Evaluation of the effect of the use of vitamin supplements on vitamin A intake among (potentially) pregnant women in relation to the consumption of liver and liver products

Objective: To assess the distribution of dietary vitamin A intake among Dutch women aged 16-50 and among pregnant women, and to evaluate the effect of the use of a vitamin A (1200 RE) containing multivitamin supplement in terms of nutritional and teratogenic risk. Study design: Data from the 2nd Dutch national food consumption survey (1992) were used for calculation of the vitamin A intake among 1725 16-50 year old women and 58 pregnant women. Calculations were performed with and without simulation of the use of a supplement containing 1200 RE vitamin A. Results: Average vitamin A intake, based on a two-day dietary record method, compared quite well with recommended intake levels: 850 RE for the 16-50 year old non-pregnant (NP) women (RDA: 800 RE), and 990 RE for the pregnant (P) women (RDA: 1000 RE), respectively. The use of liver on one of the days under survey resulted in high intakes: 60% of the women in this subgroup exceeded the 'safe upper intake limit' of 3000 RE, while in 23% of the cases intakes were > 7500 RE. Those not consuming liver or liver products on the days under survey had relatively low average intakes [NP (n = 1472): 540 RE; P (n = 46): 720 RE]; about 70% of the non-liver users had intakes below the RDA. Including the daily use of a vitamin A containing multivitamin supplement with 1200 RE resulted in intakes > RDA, while only in 2% (NP), respectively 3% (P) of the cases the 'total' intake exceeded the 3000 RE level, but remained in all cases below 7500 RE/day serving per day. Conclusion: The use of a vitamin A containing (maximum 1200 RE) multivitamin supplement can contribute to a controlled and adequate vitamin A intake and be considered as safe for pregnant women or women who wish to become pregnant, if the consumption of liver is completely avoided and the consumption of liver products is limited to maximum one

Reguliere vitamine A-supplementen veilig voor zwangeren die spaarzaam leverproducten gebruiken [Dutch vitamin A additives (1200 RE/day) safe for pregnant women consuming little liver products]

Objective. To determine how much vitamin A is consumed through liver and liver products by non-pregnant and pregnant women aged 16-50 years, and to determine the implications for the use of multivitamin products. Design. Secondary analysis on data from representative database Dutch National Food Consumption Survey. Method. Data were obtained from a Dutch National Food Consumption Survey (1992, method published earlier) regarding 1725 non-pregnant and 58 pregnant women aged 16-50 years who did or did not consume liver and (or) liver products. Results. Average daily vitamin A intake (two consecutive days), was 850 retinol equivalents (RE) for non-pregnant and 990 RE for pregnant women, respectively (recommended daily allowances are 800 RE and 1000 RE). Average intakes of those not eating liver or liver products were 540 RE and 720 RE per day. In about 70% and 50% of the women respectively the intake was below the minimal requirement of 6oo RE per day. The use of a vitamin A supplement providing 1200 RE per day among the non-liver users would in none of the cases have resulted in intakes higher than the threshold level of 7500 RE for teratogenic risks. Occasionally in 2-3% of the women, not using liver or liver products, maximum intake would exceed 5000 RE per day (the upper safe limit of intake according to the Dutch Health Council/Nutrition Council Committee). However, women using liver or liver products would be at risk of having too high intakes, above the treshold level of 7500 RE, irrespective of the use of vitamin supplements. Conclusion. Regular vitamin A supplements may be safely used by pregnant women who consume little or no liver or 1iver products. Chemicals/CAS: Teratogens; Vitamin A, 11103-57-