A Geeky Viewpoint

When it comes time to build a Box Office Projection "I" am trying to give out three numbers;     Domestic Opening Weekend, Domestic Total, and International Total; which in turn gives us the final Box Office Total.

Domestic Opening Weekend is an important metric for Film Studios (primarily the six major studios), the numbers are used to determine post release marketing strategies, number of screens booked in the next two weekends, and various other little

Domestic and International Totals are important for the secondary studios, the ones that actually make the movies, the actors, directors, and other film making staff as it determines likelihood of future budgeting, budgets for next movies, salaries and so on and so forth.

These three numbers are derived from a series of factors including but not limited too:

• Comparable Films
• Competition
• Timing on the Calendar
• Audience Fatigue
• Early Hype
• Late Hype

Lets look at "The Amazing Spider-Man 2" which will be released next week Domestically.

Comparable Films:

• Spider-Man
• Spider-Man 2
• Spider-Man 3
• The Amazing Spider-Man
• Captain America: The Winter Soldier
• Thor: The Dark World
• The Wolverine
• Iron Man 3

In this case we have a good deal of comparable films, that close fit into our current model.   Sam Raimi Spider-Man Trilogy staring Tobey McGuire, the reboot also staring Andrew Garfield (and most of the cast of this one), and four recently released Super-Hero movies in the past year.

Competition:

• Captain America: The Winter Soldier (Week 5)
• Divergent (Week 3)
• Transcendence (Week 2)
• Belle
• Walk of Shame
• The Protector 2

Here we see a direct competitor in Captain America: The Winter Soldier, two additional Sci-Fi movies still in early general release, a new Action Movie a Romantic Film and a Comedy. 
Transcendence and Divergent have proven they should be extremely minimal factors, and the audience for Belle and Walk of Shame are not the same as Sci-Fi, Super-Hero Action movie.   The Protector 2, which also will be in it first weekend, while a action movie, is a small budget sequel that virtually no one outside of its core audience is aware of.   It will be slightly more of factor in comptetion than say Belle, but not much.   The real problem for The Amazing Spider-Man 2 is Captain America: The Winter Soldier, a well received movie that going into The Amazing Spider-Man 2's opening weekend will have spent 4 weeks at number 1.   Clearly without this competition the Amazing Spider-Man 2 would do better, considering you are looking at roughly $10 million in ticket sales for Captain America: The Winter Soldier. 
I wouldn't be surprised if Captain America: The Winter Soldier finished the week in the number 2 position.

Timing on the Calendar

The first weekend in May has historically been a Super-Hero movie release date for the past half-dozen years or so.   This means it usually takes less effort to get your secondary audience in the theater because its time to see a "Super-Hero Movie"   As opposed to releasing movies in April or February.

Audience Fatigue

In the case of The Amazing Spider-Man the secondary audience is fairly fatigued.  There was the Short Turn around on the Spider-Man Reboot, there have been 5 major stand alone - single - Super-Hero movies in the past year, the sales number were way do to the previous Sam Raimi trilogy of Spider-Man Films.  

Early Hype

The Amazing Spider-Man 2 first trailer had 8 million views on YouTube in the week, it had good press on the various media, a strong social media presence.

Late Hype

While the Amazing Spider-Man 2 initial trailer had 29 million total views on YouTube, the second and third official trailer were much weaker.   Social Media presence, including retweets, blog postings are down.   The initial reviews have been lack luster. 

[Raimi's Spider-Man 2 is] among the best superhero films ever made. Marc Webb's The Amazing Spider-Man 2 is... not. Come year's end, it'll struggle to even rank among the top three superhero films of 2014.  - Simon Miraudo Film Critic Quickflix

Putting it all together

The comparable films all opened to approximately $103 million thus we have a baseline number.
While not in heavy competition, there is a very direct competitor in Genre (Captain America: The Winter Soldier - 10) and some near competitors (-4).
A traditional Super-Hero movie release weekend (+7.5)
Audience Fatigue appears to be pretty big for this movie (-25%)
Early Hype was all very positive (+10%)
Late Hype is not so good (-15%)
Total $68

So my number that I think would be the goal for $68 Million on opening weekend.   I however expect a final marketing push providing a few extra butts in the seats, so I pushed my number from $68 to $72.

I do a similar process for projecting Domestic Totals, International totals however is  little more hit or miss for me.   I can't see the Hype in Iceland or South Korea, so I rely on guidance from other sources and looking at comparable numbers.
Generally I have been fairly close (within 15% give or take) so its not a bad way to look at those numbers.

I like to point out my numbers usually in the same ballpark as major predictors like Box Office Mojo, variety and other major industry sources.   In the case of Amazing Spider-Man 2 I am within 5% of Box Office Mojo's predictions.  We differ on X-Men: Days of Future Past as they think it will do much better opening weekend than I do.

My Numbers right now for X-Men: Days of Future Past
Comparable - $87
Competition - -$9
Summer Opening - +$10
Audience Fatigue - -5%
Early Hype - +5%
Late Hype - +15%
Total $89.4 Million