A pattern formation method produces a random metal pattern that does not cause moire even when placed over a liquid crystal display and achieves improved detection sensitivity due to compressed variation in electrical properties among sensors. The method forms a patterned optically transparent and electrically conductive assembly having an optically transparent and electrically conductive layer on an optically transparent support. The conductive layer has sensor parts electrically connected to terminal parts and dummy parts not electrically connected to terminal parts, with the sensor and dummy parts having a metal mesh pattern. The metal mesh pattern has a mesh shape formed of a Voronoi diagram generated from a plurality of generators disposed on a plane, at least some of the generators in the dummy parts being present in an enlarged polygons that share the gravity center with polygons used in the tiling of the plane and/or at least some of the generators in the sensor parts being present in reduced polygons that share the gravity center with polygons used in the tiling of the plane. By these features, at least some of the polygons of the generators in the dummy parts are larger than at least some of the polygons of the generators in the sensor parts.