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Estimating individual action dispositions using binary and frequency egocentric sexual network data
Stockholm University, Faculty of Science, Department of Mathematics.ORCID iD: 0000-0003-1701-9325
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The degree distribution of nodes in a sexual network has been under thorough investigation, as has its implications for the spread of sexually transmitted infections. However, not only the structure of the network is of importance in regulating the propagation of an infection. Two nodes connected by an edge may take actions that reduce the transmission probability through that edge. Condom use is one such action. In this paper, we derive models for individual action dispositions, and how they together generate an outcome on the edge connecting two nodes. We derive two main models, one where two connected nodes generate one outcome together (suitable for casual sex partners), and one where several outcomes is allowed (suitable for steady sex partners). We model different disposition distributions and different rules on how the dispositions generate outcomes, using an egocentric network data set on condom use behaviour.

Keywords [en]
Egocentric network analysis, Social networks, Sexual behaviour, Sexually transmitted infections
National Category
Probability Theory and Statistics
Research subject
Mathematical Statistics
Identifiers
URN: urn:nbn:se:su:diva-172939OAI: oai:DiVA.org:su-172939DiVA, id: diva2:1351364
Available from: 2019-09-14 Created: 2019-09-14 Last updated: 2019-09-16Bibliographically approved
In thesis
1. Modelling Sexual Interactions: Sexual behaviour and the spread of sexually transmitted infections on dynamic networks
Open this publication in new window or tab >>Modelling Sexual Interactions: Sexual behaviour and the spread of sexually transmitted infections on dynamic networks
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis we develop statistical and mathematical models to study different factors of relevance for the spread of sexually transmitted infections (STIs). Two special interest groups for STI interventions are considered: sexually active youths and men who have sex with men (MSM). The statistical models developed make it possible to estimate individuals’ dispositions towards sexual behaviours related to the spread of STIs: condom use and anal sex. To study the spread of an infection in a population we use mathematical models. The mathematical models in this thesis give insights into the transmission process of HIV among MSM in Sweden—a population at high risk for HIV infection.

The focus of the first paper is on mechanisms giving rise to observed sexual behaviour, such as condom use, among sexually active youths in Sweden. We study the sexual dispositions of individuals and how these interact and generate the observed sexual outcomes.

The second paper concerns the sexual behaviour of MSM in Sweden and the transmission process of HIV within this population. The population is modelled by a stochastic dynamic network model that incorporates both steady partnerships and casual contacts. We model the spread of an infection where individuals are susceptible, infectious or diagnosed (unable to transmit) and derive the basic reproduction number R0, the probability of a major outbreak, and the endemic prevalence.

The third paper further develops the dynamic network model of the second paper. The model now takes into account that individuals may be sexually high-active or sexually low-active. The division into two activity groups makes it possible to study a preventive intervention against HIV that is only targeted to sexually high-active. The intervention studied is pre-exposure prophylaxis for HIV (PrEP), i.e. that the antiviral drugs tenofovir-emtricitabine are taken by individuals with negative HIV serostatus to prevent getting infected by HIV. We study the PrEP coverage needed to reduce the observed HIV prevalence of 5% to a value close to 0%.

In the fourth and final paper we focus on condom dispositions among MSM. The disposition models from the first paper are extended to better fit an MSM population and are additionally extended to be used for more types of sexual behaviour data.

Place, publisher, year, edition, pages
Stockholm: Department of Mathematics, Stockholm University, 2019. p. 40
Keywords
Mathematical modelling, Sexually transmitted infections, Egocentric network analysis, Dynamic networks, Sexual behaviour, HIV, Statistical inference
National Category
Probability Theory and Statistics
Research subject
Mathematical Statistics
Identifiers
urn:nbn:se:su:diva-172941 (URN)978-91-7797-857-2 (ISBN)978-91-7797-858-9 (ISBN)
Public defence
2019-11-28, sal 14, hus 5, Kräftriket, Roslagsvägen 101, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2019-11-05 Created: 2019-09-16 Last updated: 2019-10-22Bibliographically approved

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