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Measuring fragmentation in PNG’s parliament

PNG's parliament in session - it is one of the world's most fragmented parliaments

| DevPolicy Blog

PORT MORESBY - Papua New Guinea has many parties in parliament, which makes for both a fragmented parliament and a fragmented government.

PNG has one of the most fragmented parliaments in the world. In a previous article, I calculated parliamentary fragmentation using an index known as the effective number of parties (ENP).

The ENP weights the number of parties according to the total number of seats won, thus giving a higher weight to larger parties.

Parliaments that are fragmented across many, small parties will have higher ENPs than parliaments with a few parties or parliaments with many parties but which are dominated by a smaller subset.

Using the ENP, the parliament’s fragmentation after the 2017 elections was high: 6.9 if calculated with independents excluded, or 9.1 with independents included and treated as separate ‘parties’.

This puts PNG among a very small group of countries globally with highly fragmented parliaments: Belgium (9.7), Bosnia and Herzegovina (8.7), Brazil (16.5), Indonesia (7.5) and the Netherlands (8.1).

However, PNG’s ENP hasn’t stayed static throughout the political cycle of this parliament.

The number of parties in parliament began at 21 in 2017 and has grown since. and ministries

The ENP, however, has fluctuated and is now actually lower than it was in 2017.

(My calculations here and in the rest of this article are made including independents as if they were individual parties. Trends do not change much if independents are excluded.)

What is interesting about the chart below is that the ENP fluctuated, first as government was formed following the 2017 elections, and then around the two votes of no confidence: the first, which saw James Marape replace Peter O’Neill as prime minister in May 2019; the second, an unsuccessful attempt against Marape, in December 2020.

Laveil 1
Effective number of political parties (ENP) in Papua New Guinea's tenth parliament.
VONC = vote of no confidence

The ENP has fluctuated because many members of parliament change parties during the turbulent times of government formation and votes of no confidence.

One blog noted that 76 MPs had switched parties at least once since 2017.

When O’Neill formed government in August 2017, the ENP fell from 9.1 to 4.2 as his party, People’s National Congress (PNC), grew in number from 29 to 48 MPs.

The ENP increased to 7.29 during the first vote of no confidence, then rose slightly to 7.34 during the second.

The ENP increased again to 8.2 in 2021, reflecting the aftermath of the second vote of no confidence, before falling to 7.1.

The PNG MP Database also, for the first time, enables fragmentation within government coalitions to be measured.


The effective number of parties index includes MPs in government that belonged to parties split between government and opposition.

O’Neill formed government with an ENP of 3, reflecting a coalition including the three largest parties - PNC (48 MPs), PANGU (13 MPs), United Resources Party (11 MPs).

The ENP then rose to 6.5 during the first effective number of parties vote of no confidence when O’Neill was ousted by Marape, before falling to 3.5 during the second.

After the first vote of no confidence, Marape’s PANGU party remained the largest, averaging 29.5 MPs till present.

However, his government is more fragmented compared to O’Neill’s, thanks in part to the inclusion of several relatively large parties: National Alliance, URP, United Labor Party and People’s Party.

The government’s ENP rose to 5 in 2021 after Marape’s coalition survived the second vote of no confidence, and has maintained that level until now.

A further measure of fragmentation of government coalitions that can be calculated is the policy coherence index (PCI).

The PCI measures the amount of political influence each coalition party wields by calculating the probability that ministries will be awarded to different parties.

The index ranges from 0 to 1, a PCI approaching 1 indicates that cabinet (the ministry) is more fragmented across parties.

As the chart below shows, the PCI and the number of parties that were awarded ministries trend together.

In 2017, with less fragmentation within government (PCI = 0.48), O’Neill was able to appoint his cabinet from only five parties (despite having 14 parties in government).

The PCI then increased to a high of 0.82 during the first vote of no confidence, reflecting ministries awarded to 11 parties in Marape’s government.

The PCI then fell to 0.76 as Marape warded off the second VoNC, reflecting eight parties awarded ministries in a cabinet reshuffle.

Since February 2021, the PCI has been 0.77 with 11 parties awarded ministries.

Calculating the fragmentation of parliament and government is instructive, as PNG’s political history is replete with votes of no confidence.

In the past, three prime ministers have been replaced by a vote of no confidence: Somare in 1980, Somare in 1986 and Wingti in 1988,

Three others have resigned to avoid a vote of no confidence (Wingti 1993, Skate 1998, and O’Neill 2019).

During PNG’s tenth parliament, forming government after the election led to a less fragmented parliament and government while both votes of no confidence led to greater fragmentation of parliament and government.

The 2022 elections will likely see many parties elected, making parliament highly fragmented once more.

Government, when formed, is likely to be less fragmented as MPs switch parties to join the largest party.

However, once the 18-month grace period ends, and another vote of no confidence ensues, fragmentation within parliament and government may once again change.

This research was undertaken with the support of the ANU-UPNG Partnership, an initiative of the PNG-Australia Partnership, funded by the Department of Foreign Affairs and Trade. The views are those of the author only


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