While the weather has been glorious for all of five minutes this year, parents all around the UK will be fearing another turn for the worse as the long summer school holidays approach.

If these gloomy predictions turn out to be accurate I will not be the only parent checking the cinema listings to see which films I can take the children to see to on a rainy afternoon. Indeed, my family have been known to take our children to see films such as Ice Age, Scooby Doo and Batman et Robin to escape our soggy tent when camping in the rain in France, despite the films being in French and us only having elementary French language skills.

But the film industry is serious business, as evidenced by the budget and revenue figures that can be found on the Internet Movie Database. So much so that I and my Lancaster University Management School colleague Rob Simmons have just completed a study of 527 films to build a statistical model of the factors that determine box office success. Our findings provide a new source of intelligence for film professionals armed with multi-million pound advertising and marketing budgets - intelligence that was not previously available.

One of the results that struck us was that family-orientated films with U certificates do so well - enjoying more than 68% higher revenues than films with other certificates. Not only is a trip to the cinema a good way to entertain kids when the weather is bad, but each trip typically involves multiple tickets to a film: young children need adult accompaniment and this raises box office revenue.

Large advertising budgets are crucial for box office success. Interestingly, we found that UK advertising is greater for films with higher US opening revenues and higher budgets. Films released simultaneously in US and UK attract greater advertising while a longer gap between the US and UK releases leads to less advertising. This suggests a perception by distributors that films which are delayed in release after US opening do not merit advertising as they will not pay off in the UK box office. That's why Sex and The City: The Movie, which is being launched in the UK and US on very similar dates, should make millions - even if it doesn't turn out to be the greatest film of all time.

The fact that a film is a sequel can also allows the public to better predict if the follow-up film is likely to suit their personal tastes. Our results, unsurprisingly, confirm that sequels also tend to do well at the box office. But the key finding here is that sequels can ead to box office revenues almost 50% greater than fpr other films. There is much hype about the new Indiana Jones movie, 14 years on from the last film; coupling this hype and the fact that the film is a sequel will give it a key advantage.

Favourable reviews in newspapers - an early indication of a film's quality when it is first released - can increase box office revenues directly by 14.5%. So budding Barry Normans really can make or break a film. Word-of-mouth opinions and critical reviews can ensure that films do badly at the box office despite large investments and the use of well-known actors. Consider, for example, the recent relatively weak opening figures for Speed Racer compared to Iron Man, and such films as Glitter in the US and Eyes Wide Shut.

Any filmmaker keen to have a box office hit should consider making a family-orientated film that may appeal to critics, marketed using a large advertising budget. However, crucial for filmmakers in the UK, we find that British films do 5% better if they are distributed by one of the major studios, with the initial number of screens allocated to these films 20% higher than for films distributed independently.

Everyone is currently talking about Indiana Jones and Sex and the City - but, based on, our findings, I have high hopes for Kung Fu Panda. A children's film, with A-list celebrities such as Jack Black, Jackie Chan and Dustin Hoffman providing the voice-overs, this was promoted at the Cannes Film Festival with pretend fighting people dressed in giant panda costumes. Watch this space, but Kung Fu Panda could go unnoticed and become this year's real hit.