Question

ch 8 although web surveys are becoming more frequent, many of them still suffer from which type of bias?
under-coverage bias
non-response bias
volunteer response bias
question 11
1 pts
ch 9 __________ refers to having multiple independent experimental units in each treatment group.
comparison
replication
randomization
blocking

Explanation:

For the first question (about web survey bias):

Under - coverage bias occurs when some members of the population are left out of the sampling frame (e.g., people without internet access in web surveys). Non - response bias is due to people not responding to the survey, and volunteer response bias happens when only those who volunteer (self - select) to take the survey respond, which is common in web surveys as people choose to participate. So these three biases are common in web surveys.

Replication in experimental design means having multiple independent experimental units in each treatment group. Comparison is about comparing groups, randomization is about randomly assigning units to groups, and blocking is about grouping similar units. So the correct term is Replication.

Answer:

under - coverage bias, non - response bias, volunteer response bias

For Question 11: