The team's study looked at ratings of the top 1,000 apps on the App Store, showing thatmore than half of the top 1,000 apps have a rating of at least 4.5 out of 5 stars, with 75% scoring 4 stars or higher.

Appurify found the higher an app is placed in the charts, the more the ratings seem to matter. For example, in order to reach the top 300 of all apps in the marketplace, app makers will need hundreds of 4.5- and 5-star reviews every single day, but making the list of top 300-600 apps is not nearly as tough. 

The team also found fixing bugs and performance lead to big changes in an app's ratings.

"The importance of fixing bugs during the software update cycle cannot be overstated," the group said in a blog post.

"Or better still, taking care of bugs, crashes, and performance issues prior to release can make a huge positive impact on reviews and ratings. The majority of negative reviews are performance related and can pull your app down."

• 75% of the top 1000 apps have 4+ star rating
• It is important to test apps for bugs/crashes and performance issues prior to release and before every software update
• Remember to check for performance issues when pushing updates–a low-performing update can tank your rating
• Higher-rated apps attract more favorable attention and are more likely to get more reviews and ratings following software updates
• It’s not enough to just get to 4 stars. The uptick in ratings activity between 4 and 4.5 stars (and higher) is significant
• App ratings and rankings are inter-related. The higher you move up the rankings ladder, the more app star ratings matter.

For the full picture check out Appurify's blog here.