Identify which threat(s) are present in each of the examples below with brief rationale.

Please note threat first in BOLD followed by rationale.

NOTE: There may be more than one IV threat that applies for some

1. A convenience sample of post-operative hysterectomy patients on surgical unit at one hospital were randomly assigned to one of two groupsan experimental group receiving a special new aromatic massage protocol to enhance post-op comfort, or the control group receiving the usual care (warm compress protocol). Of the 62 patients assigned to the experimental group, 60 completed the protocol and the Post-Op Comfort Questionnaire while 18 of the 60 patients assigned to the control group did not complete the protocol. Results showed that the experimental group reported higher levels of post-op comfort compared to the control group.

NOTE: For this example, there is also an issue related to external validity. What is it?