Personal Safety App Effectiveness - Mike Just; Hasmeet Chandok; Raghav V. Sampangi; Kirstie Hawkey; Alette Willis; JeyaBalaji Samuthiravelu; Dilpreet Gill; Michael Altair (Extended Abstracts of the 2019 CHI Conference on Human Factors in Computing Systems, CHI 2019, Glasgow, Scotland, UK, May 04-09, 2019, 2019)