Choice-based sampling is one of the stratified sampling strategies. In choice-based sampling,  the data are stratified on the target and a sample is taken from each stratum so that the rare target class will be more represented in the sample. The model is then built on this biased sample . The effects of the input variables on the target are often estimated with more precision with the choice-based sample even when a smaller overall sample size is taken, compared to a random sample. The results usually must be adjusted to correct for the oversampling.
3. Working Hypothesis: Mihaly Fenscak was born in Posa, Slovakia, married there and had two children. His first wife died and then he married Illa. Their first child was born in Liverpool, England, and then they arrived in America. While in Freeland, Pa., their daughter Anna was born, and then they eventually returned to Slovakia where their final two children, Elizabeth and Michael were born. Mihaly and Illa both died in Slovakia. Their three daughters eventually settled in America, and their son in Argentina. Mihaly’s children from first wife: John settled in America; Anna stayed in Slovakia and married.