Taking a look at the UX case study that was done by Johny Vino for the New York Times app, my observations are thus;
<ol>
<li>For a case study to be valid, it has to identify a problem that will be solved at the end of the whole exercise.
</li>
<li>It has to have goals that are SMART i.e. Specific, Measurable, Attainable, Realistic and Time-bound.
</li>
<li>A valid case study has to follow the design process iteratively i.e. stages can be repeated as much as possible until the desired result is achieved.
</li>
</ol>

Taking a look at the UX case study that was done by Johny Vino for the New York Times app, my observations are thus;

1. For a case study to be valid, it has to identify a problem that will be solved at the end of the whole exercise.
    
2. It has to have goals that are SMART i.e. Specific, Measurable, Attainable, Realistic and Time-bound.
    
3. A valid case study has to follow the design process iteratively i.e. stages can be repeated as much as possible until the desired result is achieved.

My Review on the Redesigning the New York Times app