Final answer:
The study conducted by the web designer is an experiment with a major flaw being a small, non-random sample size. The target population is all users of the online shopping cart, but the sample represents the designer's colleagues, and the data collected is quantitative.
Step-by-step explanation:
The web designer's study is best categorized as an experiment rather than an observational study because there is a deliberate manipulation of the independent variable, which is the interface design of the online shopping cart system.
The major flaw in this study could be the small sample size and the lack of random sampling. The sample is not likely representative of the entire user base of the shopping cart system but only of the designer's colleagues. Moreover, the colleagues from the same office might share a similar level of expertise or biases, which could influence the results.
The target population of the study is presumably all users of the company's online shopping cart system, but the sample is actually representative only of the design office colleagues.
The data collected is quantitative as it involves measuring the time it takes to complete an order, which can be quantified.
The sampling method used here appears to be convenience sampling, as the designer has selected a small, easily accessible subset of the population rather than using a method that could result in a sample more representative of the entire user base.