How the Senedd is Elected
The National Assembly for Wales, now renamed the Senedd, has 60 members, with 40 elected to represent constituencies and 20 elected to represent regions. Voters at Senedd Elections have two votes, one for constituencies, and one for the regions.
The 40 constituency members are elected using the First Past the Post system where the winner is simply candidate who gets the most votes.
The remaining 20 members are elected using the regional votes to make up the 4 seats in each of the 5 regions: North Wales, Mid and West Wales, South Wales West, South Wales Central, South Wales East. The regions each includes 8 constituencies, and the system is designed to ensure that the seat allocation adds an element of proportionality. This means that if a party wins lots of constituency seats in a given region, it is less likely to win an additional regional seat, whilst smaller parties are more likely to win seats through the regional list system.
The 20 regional seats are allocated via the Additional Member System, which uses the d’Hondt method to allocate seats, and works like this:
- Each party selects a list of up to 4 candidates for the region, and voters cast their ballot for the party of their choice in the regional vote.
- The total number of votes that the party receives across the region is divided by the number of constituency seats that the party won in that region, plus one (a mathematical adjustment in order that no number is divided by zero).
- The party with the largest total following this first calculation is awarded the first additional seat for that region.
- The calculation is then repeated for the second, third and fourth additional members, in each case dividing the party list vote by the number of constituency seats, plus one, plus any additional regional seats allocated in previous rounds.
Sut mae'r Senedd yn cael ei Hethol
Mae gan Gynulliad Cenedlaethol Cymru, sydd bellach wedi'i ailenwi'n Senedd, 60 aelod i gyd, 40 wedi'u hethol i gynrychioli etholaethau ac 20 wedi'u hethol i gynrychioli rhanbarthau. Mae gan bleidleiswyr yn Etholiadau’r Senedd ddwy bleidlais, un ar gyfer etholaethau, ac un ar gyfer y rhanbarthau.
Etholir y 40 aelod etholaethol trwy gyfrwng y system Cyntaf i’r Felin lle mai'r enillydd yw’r ymgeisydd sy'n cael y nifer fwyaf o bleidleisiau.
Etholir yr 20 aelod sy'n weddill gan ddefnyddio'r pleidleisiau rhanbarthol i ffurfio'r 4 sedd ymhob un o'r 5 rhanbarth: Gogledd Cymru, Canolbarth a Gorllewin Cymru, Gorllewin De Cymru, Canol De Cymru, Dwyrain De Cymru. Mae 8 etholaeth ymhob rhanbarth, ac mae'r system wedi'i chynllunio i sicrhau bod y dyraniad seddi yn ychwanegu elfen o gymesuredd. Golyga hyn os yw plaid yn ennill llawer o seddi etholaethol mewn rhanbarth penodol y bydd yn llai tebygol o ennill sedd ranbarthol ychwanegol, tra bod pleidiau llai yn fwy tebygol o ennill seddi trwy'r system rhestrau rhanbarthol.
Dyrennir yr 20 sedd ranbarthol trwy'r System Aelod Ychwanegol, sy'n defnyddio'r dull d’Hondt i ddyrannu seddi, ac mae'n gweithio fel hyn:
- Dewisa bob plaid restr o hyd at 4 ymgeisydd ar gyfer y rhanbarth, ac mae pleidleiswyr yn bwrw eu pleidlais ar gyfer y blaid o'u dewis yn y bleidlais ranbarthol.
- Rhennir cyfanswm y pleidleisiau a dderbynia plaid ar draws y rhanbarth â nifer y seddi etholaethol a enillodd y blaid yn y rhanbarth hwnnw, ynghyd ag un (addasiad mathemategol er mwyn gofalu na rennir yr un rhif â sero).
- Y blaid sydd â'r cyfanswm mwyaf yn dilyn y cyfrifiad cyntaf hwn sy'n derbyn y sedd ychwanegol gyntaf ar gyfer y rhanbarth hwnnw.
- Yna ailadroddir y cyfrifiad ar gyfer yr ail, trydydd a'r pedwerydd aelod ychwanegol, gan rannu pleidlais rhestr y pleidiau â nifer y seddi etholaethol ymhob achos, ynghyd ag un, a hefyd unrhyw seddi rhanbarthol ychwanegol a ddyrannwyd mewn rowndiau blaenorol.