Gopal Menon

Advantages of CUSUM chart over Individual, X BAR chart
 
1. CUSUM chart is used to detect smallest variation from target value. This chart is used where sub grouping is not required / feasible, however, there is a need to detect very small shift (less than 1.5 sigma). The biggest advantage is that the user can determine the degree of shift that needs to be detected
This type of chart can also be used where the process average is expected to naturally shift, for e.g. chemical industries
2. This chart is a better choice when the objective is to control the data point to a target value by making necessary process adjustments than plotting an X Bar or Individual chart and then trying to identify special causes for variation
Example using data (reference source from Cumulative Sum Chart (CUSUM) - Six Sigma Study Guide)

Minitab or other SPC tools can auto calculate the upper and lower CUSUM for all values
 

 

CUSUM chart shows that the process is deviating from target from sample 13, whereas, the below IMR chart shows that process is in control and is stable. Hence CUSUM chart is more useful to detect small changes in the process mean compared to X Bar and I MR charts

 

Explain card sorting
Card sorting is a UX research technique used to organize the content in the most logical and user friendly way so that it positively impacts user experience when accessing a website or an application of a product or service. For. e.g. When building a mobile app, card sorting can help the UX team to determine what content has to be presented in each screen. The objective is to make the application easy for users to navigate and fulfil their expected outcomes by improving their experience. 
Use examples to show how it is different from an Affinity Diagram
Though at a high level both card sorting technique and affinity diagrams focus on brainstorming and grouping / classifying inputs into various groups / themes, the usage context is different.
Let's take a fashion / clothing website for example
 
Card sorting as a technique, in this case, can be used to to understand the requirements from the users and categorize the requirements under various themes or headings. E.G. one of the main heading or theme (out of many) can be Men's clothing and the sub themes can be Jackets, Shirts, Trousers etc. Affinity diagram can be used to understand what did users buy at a competitor website, what are the items they could not find in the website, which other website would they visit to make a purchase etc. Affinity Diagram can also be used to brainstorm on solutions. 
However, one of the main difference between card sorting and affinity diagram is that card sorting also- focuses on structuring the content. E.g, "Home" can be the first heading (followed by sub headings), "Contact us" can be the last heading whereas Affinity Diagram only focuses on grouping and prioritizing of ideas