I used the precinct-level results from the Hawaii government along with Wessa's online regression software (Wessa P., (2008), Multiple Regression (v1.0.26) in Free Statistics Software (v1.1.23-r7), Office for Research Development and Education).

Introduction:

I hope no one's offended by my title. I'm in the "netroots bubble" too--it's simply the consequence of trying to follow lots of races all over the country and support candidates that seem to agree with us on the issues we think are important, which are probably national issues.

There's nothing wrong with that, but there's always the possibility that we're over-looking important local factors that don't correlate with our own ideological emphases. (And hopefully some locals will stop by this diary and tell me if I'm on the right track--that's one of the great things this community can offer.)

DKE, and national activists in general, seemed to have clear opinions on the Hawaii Congressional primaries.

Despite Tulsi Gabbard's lousy history on gay rights, liberal activists seemed to mostly line up behind her--she had the endorsements of the Sierra Club and Dennis Kucinich--especially since her opponent, Mufi Hannemann, is currently to her right on social issues.

Meanwhile, Mazie Hirono is one of the most liberal members of Congress--her Progressive punch score is the 8th highest in the House!--and her opponent was a former member of the Blue Dog caucus.

Despite this, the Maui News noted:

Kahului was the single state House district Mufi Hannemann claimed in his losing bid to Tulsi Gabbard in Saturday's Democratic primary race for the 2nd Congressional District, according to a geographical analysis of voter results.

Hannemann bested Gabbard by a margin of 50.9 percent to 43.2 percent in Maui's state House District 9 - which includes Kahului, Wailuku and Puunene.

[...]

Hannemann's popularity with Central Maui voters could explain why the former Honolulu mayor and his wife, Gail, chose to spend Saturday afternoon sign-waving in Kahului near the intersection of Kuihelani Highway and South Puunene Avenue. Hannemann later spent most of the evening at the Maui headquarters of the International Longshore Workers Union in Wailuku before flying back to Oahu to watch the election results play out.

[...]
Among Maui's six House districts, Gabbard did best in South Maui's District 11, with 58.9 percent of those votes. (The breakdown of votes by district includes absentee ballots counted in the precinct where the voter lives.)

Among the 27 voting House districts, Gabbard had the highest percentage of votes in Kaneohe Bay and Kailua on Oahu, with 66 percent of votes in District 50.

[...]

Hirono, meanwhile, defeated Ed Case in the Democratic primary race for U.S. Senate.

She, too, fared best - in terms of percentage - in the Kahului-Wailuku-Puunene state House district, according to an analysis of precinct votes.

Hirono got 75.8 percent of the vote to Case's 23 percent in Maui's state House District 9 - the largest margin she won among the state's 51 House districts. She performed second-best statewide in Maui's House District 8, which includes Wailuku, Waihee and Waikapu, with 71 percent of votes.

Similarly, the Honolulu Civil Beat noted:
Kailua's state House district was unique in three ways in Hawaii's three biggest primary races Saturday:

District 50 was Ed Case's few bright spots in his blowout loss against Mazie Hirono.

District 50 was the site of Tulsi Gabbard's largest victory margin over Mufi Hannemann in the 2nd Congressional District primary.

District 50 was one of Ben Cayetano's strongest bases of support in the Honolulu mayor's race.

The electoral map shows Hannemann won just one of 27 districts: central Maui, where he spent much of Election Day rallying with union supporters.

You can click through for their take on the geographic results; and the Maui News also noted the Kailua thing. (Kailua, it must be pointed out, is where many of Tulsi Gabbard's donors tied to her anti-gay father live, but these are not people who I'd expect to be inclined to donate to Ed Case, who had a nasty race against Mike Gabbard back when he was a Republican. By the way--I hesitate to link to that diary, since I really should add some more detailed citations of the Rick Ross forum people to it.)

After twohundertseventy asked me the Hirono/Case correlation, I decided to find out--at the precinct level.

Precinct-Level Regression:

Here is a chart I made comparing Mazie Hirono's vote share by precinct (which might include some "precincts" of miscellanious absentee ballots or what-have-you):

As you can see, the negative correlation is weak, but it's hard to miss. Wessa's regression analysis gave me:

Gabbard[t] = + 0.838436227246869 -0.470061633617915Hirono[t] + e[t].

The r-squared was a miniscule 0.24, but the Hirono variable was highly statistically significant in explaining the Gabbard variable.

Specifics and Explanations:

The easiest guess, for me, is that this is about two related factors: labor support and establishment/outsider dynamics.

Look at the Civil Beat's list of endorsements. While Hirono, Case, Gabbard, and Hannemann all had some union support, Hirono and Hannemann seemed to definitely be labor's candidates overall: Hirono was endorsed by the AFL-CIO, by the Hawaii Fire Fighters Association, the Hawaii Government Employees Association, the Hawaii Laborers’ Union Local 368, the Hawaii Regional Council of Carpenters, the Hawaii State Teachers Association, the International Longshore and Warehouse Union (ILWU) Local 142, and the United Public Workers. Except for the AFL-CIO, all of these also endorsed Hannemann--and he had more labor union support besides.

Both the Civil Beat and Maui articles mentioned how Hannemann spent election night partying with labor groups in the Maui district where both he and Hirono did very well.

More subjectively--despite having different ideological emphases (and a vicious personal feud!) Gabbard and Case were both the "outsider" candidates in some sense.

Much of Ed Case's campaign message seemed to be about how he wasn't a part of Hawaii's hegemonic Democratic establishment. (Indeed, a very liberal friend of mine from Hawaii once expressed a positive opinion of Case on these kinds of grounds, much to my surprise). For example, here's his pre-primary message from his website:

But beyond that, the Democratic primary election tomorrow asks you to choose between the status quo and change.

It asks you to decide whether you think DC is working today or whether it is broken and must be fixed.

And it asks you to decide whether the political culture of Hawai'i is working for all or whether we can and must do better.

Hirono, while very liberal, is also very much a part of the Hawaii establishment.

In some sense, Hannemann was an outsider as well--I recall reading an article or blog post that pointed out how he'd always done better in the nonpartisan Honolulu municipal elections than in Democratic primaries.

But he was a major figure in state politics, and a lightning rod for various controversies, and Gabbard--a young, telegenic veteran--presented herself as a "fresh approach" to "the tired old politics of sweetheart deals and trading favors [and so on]".

And, of course, there's a relationship between being the labor candidate and being the establishment candidate, especially--it seems to me--in a state like Hawaii. This obviously isn't statistically significant, but the Civil Beat intriguingly interviewed a few voters at one location:

Bryan Costa, a 29-year-old Democrat, said that he voted for Gabbard because he doesn’t like Mufi Hannemann.

“I don’t care for Mufi,” the Waimanalo resident said. “I’m against rail, and I’m a small business owner and anti-union. Mufi has all the union support.”

[...]

Enchanted Lake Democratic resident Shannon Kaopua, 44, voted for Gabbard because he “wanted to try something different.”

Gabbard, as far as I know, supported the rail project as a councilmember, but has expressed skepticism about it in various ways, while Hannemann was such a strong supporter that it's been called "Mufi Hannemann's rail". And voters who feel strongly about rail were surely out in force, since the mayoral primary:
As the Pacific Business News explains, [Mayoral candidate] Cayetano "campaigned on an anti-rail platform that turned the race into a referendum on the city's $5.16 billion rail transit project." Both Caldwell and Carlisle are apparently pro-rail.
On the other hand--if I squint, Cayetano's precinct-level performance looks like it has a negative relationship with Hirono's or with Hannemann's (on the handful of precincts in both Honolulu and HI-02), but Wessa tells me these aren't statistically significant. So maybe there's more going on.

Let's go back to the Civil Beat, since they'll be better at giving context to the specific locations:

Case won just four of 51 districts statewide: Kailua, Hawaii Kai, East Honolulu and Waikiki.

[...]

The wealthier areas Case won could be tough for Hirono in November. There were 13 House districts where Hirono secured between 50 percent and 55 percent of the Democratic Party primary vote, including the Waialae seat currently held by retiring Republican Barbara Marumoto and other districts across the Windward side and southern shore of Oahu. 

None of those relative weak spots — emphasis on relative — were on neighbor islands.

Case won only a few precincts--42-03, 48-03, 49-05, 49-06, 50-01, 50-02, 50-03, 50-04, 51-02, 51-03, 51-04. Gabbard did quite well in all of these, with the exception of 42-03, which she won, but by less than her overall numbers. And with the exception of 42-03, these were all in districts near her City Council seat--the sixth, so they might simply be familiar with her.

Back to the Civil Beat:

Hannemann's defeat was nearly universal, with his only district win in 27 opportunities coming in District 9, which includes portions of Wailuku and Kahului on Maui. Hannemann was waiting for the first printout results at a union hall there Saturday, but delays on the Big Island meant he had to leave before the numbers were in.

Hannemann only reached 40 percent support in four other districts — another on Maui, two on Kauai and the North Shore of Oahu.

It's kind of fascinating that the former Honolulu Mayor did best on the Neighbor Islands--which means that geographic familiarity might not be all that's going on here.

Following the same standard, Hannemann got 40 percent or more in the following precincts:

01-03
02-04
02-05
03-01
03-02
03-03
03-07
05-01
08-03
08-04
08-05
08-06
08-07
09-01
09-02
09-03
09-04
10-03
10-04
12-04
13-09
14-05
15-02
15-03
15-04
16-01
16-03
16-04
16-05
16-06
45-05
46-02
46-03
46-04
47-03
OS 2.
Hirono did far better than her overall results in nearly all of these. (I'm told that Ed Case is from Hilo.)

Here's the Maui News, back when Hannemann was endorsed by the ILWU Local 142:

In a news conference, Hannemann said he was "humbled and honored" to receive the backing of Hawaii's largest private-sector union, with 20,000 members statewide and around 15,000 on Neighbor Islands.

That certainly suggests the labor's clout is strongest on the Neighbor Islands--and many of these strong Hannemann/Hirono precincts are there as well. House Districts 1-7 are on the Big Island, while 8-12 are on Maui, and 14-16 are on Kauai. The rest seem to be on what the Civil Beat called the "North Shore" of Oahu--and what seems to be the more rural part of Oahu.

Conclusion:

The simplest interpretation of the 2010 Hawaii Democratic primary results is that both of the most liberal candidates won. And that's true--and many voters surely voted Case/Hannemann or Gabbard/Hirono.

But there's significant evidence that there was a different dynamic going on, and one that didn't follow the sort of liberal/conservative dimension that we tend to focus on. It might have had something to do with one or more of the following interlocked factors:

-The local rail project.
-Labor union support.
-Instate vs. outstate.
-Party outsiders vs. party insiders.

And those are just my guesses. Again, I'd be very interested to know more, since I know we have some really knowledgeable Hawaiians on this site. I'm very interested. Who would have ever thought that Ed Case and Tulsi Gabbard would have any kind of correlation about anything?

6:15 PM PT: I only remembered this in the comments, but the 46th and 47th House Districts are where, as Inoljt pointed out, Mitt Romney did very well in the Hawaiian caucuses. There's a Mormon temple there, at Laie, and Hannemann is a Mormon.