“…Given the limitations of the interpolation technique and no single statistical distribution that fits the entire income distribution, numerous studies have suggested a variety of parametric functional forms to directly estimate the Lorenz curve. Examples include Kakwani andPodder (1973, 1976), Kakwani (1980), Rasche et al (1980), Aggarwal (1984), Gupta (1984), Arnold (1986), Rao and Tam (1987), Villaseñor and Arnold (1989), Basmann et al (1990), Ortega et al (1991), Chotikapanich (1993), Rao (1996, 2000), Ryu and Slottje (1996), Sarabia (1997), Sarabia et al (1999Sarabia et al ( , 2001Sarabia et al ( , 2010Sarabia et al ( , 2015Sarabia et al ( , 2017, Sarabia and Pascual (2002), Rohde (2009), Helene (2010), Wang and Smyth (2015), Fellman (2018), Tanak et al (2018), Paul and Shankar (2020), and Sitthiyot et al (2020). However, many existing widely used functional forms often cited in the literature do not have a closed-form expression for the Gini index, making it computationally inconvenient to calculate since they require the valuation of the beta function, for example, Kakwani and Podder (1976), Kakwani (1980), Rasche et al (1980), andOrtega et al (1991), or the confluent hypergeometric function, for example, Rao and Tam (1987).…”