Identify the sampling issues that are problematic in online surveys:

(A) Many people use more than one internet service provider.

(B) Every person has only one (unique) email address.

(C) A house hold may have one computer but several users.

(D) Internet users are a biased sample of the population.

Choose the correct answer from the options given below:

The correct option is (A), (C) and (D) Only.

Let us analyze each statement to understand why it represents a sampling issue that is problematic in online surveys:

(A) Many people use more than one internet service provider (ISP):
This is a sampling issue because a single individual might have multiple access points or accounts across different ISPs. This can lead to double-counting or unequal probabilities of selection, violating the basic assumption of probability sampling where each member of the population should have a known, typically equal, chance of being selected.

(B) Every person has only one (unique) email address:
This statement is factually incorrect. In reality, many individuals own and use multiple email addresses (e.g., personal, work, school). If every person did have exactly one unique email address, it would actually make sampling easier and less problematic. Therefore, this statement is not a problematic sampling issue of online surveys.

(C) A household may have one computer but several users:
This presents a selection and response bias issue. When a survey invitation is sent to a shared device/household computer, it is difficult to control or determine which specific member of the household completes the survey. This leads to issues in identifying the actual respondent and defining the unit of analysis.

(D) Internet users are a biased sample of the population:
Online surveys suffer from coverage bias. Not all segments of the general population have equal access to the internet (e.g., elderly populations, individuals in rural areas, or low-income groups may be underrepresented). Therefore, a sample drawn only from internet users is biased and cannot be easily generalized to the entire population.

Thus, statements (A), (C), and (D) are genuine sampling issues that make online surveys problematic, making (A), (C) and (D) Only the correct choice.