Singing Study Comments

1. Based on the description of sampling procedures,participation bias could occur in this study.

2. Also, secured-ward participants who sang or did not sing were assigned through observation of participation level. This can occur reporting bias.

3. In addition, the tests are held by assessors and I have not seen any information indicating this experiment is double blinded. In this case, interview bias can occur in this study.

1) Spectrum bias. Didn't see much reporting on stage of Alzheimer's disease in the patients. This could alter results drastically if not representative of general Alzheimer's population (further question, what is this??).

2) Not sure name of the bias, but outside factors could have an influence on happiness/well being. Could be so many other factors involved (maybe potential reporting bias)

3) Attrition Bias. Admitted that this occurs in paper. Loss of participants due to death, transfer to other facilities etc. This could be due to factors such as well being, so could cause lost information.

1) There is participation bias as only Alzheimer's patients in the ECE facility were selected as a sample for all the population of Alzheimer's patients.

2) There is observer bias as the researchers allowed their hypothesised results to influence their sampling and assignment (i.e., they used a "natural assignment" rather than random assignment).

3) Finally, confounding bias is also present as the experimenters did not properly correct for much of what happened between the 4-month testing period, including the norovirus outbreak (although they do note that this might have influenced their results).

1) Measurement bias: As the study measurement is based on cognitive assessments, which is hard to measure quantitatively and accurately. 2) Omitted variable bias: Environmental control is essential in this study. However, some covariates are hard to control, or are not realized by researchers. Therefore, omitted variables may cause bias of the study . 3) Selection bias: The people who participant in this study may tend to love music, therefore, the sample is not representative. Besides, sample size N = 45 is too small.

1) Selection bias: the researcher did not randomly assigned patients into groups. Since they are consider pre and post measurements, the singer and listener groups may not be comparable at baseline.

2) Volunteering bias: the participants decided whether they want to be in the study or not.

3) Technical/Information (?) bias: participants were reduced from 73 to 45. Moreover, the control group was not considered in the study. Only two types of different treatment were considered, but no comparison was given regarding of the difference between treatments and controls.

1. The singing or listening category one participate belongs to is based on the research assistants' observation. This may lead to an error while observing and recording, or measurement bias. 2. The music can change the listeners' mood and emotional experience that may affect the result. This may be a confounding bias. 3. During the period of the Norovirus and quarantine, the virus only affected the Assisted-living groups, may also lead to a bias.

Their "natural assignment" might cause those who are more likely to remember things like lyrics to participate more, which would place them in the singing group.

The participants all came from one location, which makes it harder to generalize. Subjects were recruited based on their willingness to participate, along with the lack of randomization for treatments, makes this even harder to generalize.

Possible lack of double blinding meant researchers may influence the results to better prove their hypothesis. This is especially true for the Clock Drawing test which is more subjective to interpretation.

Participants were housed together which meant they could influence each other. Clearly not independent.

1. Researcher bias: see thesis page 16: The researcher actively participated and interacted with volunteers in the study. " The leader would often step away from the piano to rehearse the singing while encouraging posture, upper torso buoyancy, breath intake and support, vowel and rhythmic integrity, discussing interpretation and integrity of texts, etc."

2. Technical bias: should the researcher use time since first diagnosis as a proxy to measure disease progression to test for confounding. ie. there may be critical points where no reversibility of the disease is possible and the treatment applied here assumes that each patient is on the same prognosis pathway.

3. Bias exists in the presidential question or in some of the other cognitive tests towards those who previously knew past presidents or had an ability to spell.

• It is suspicious that the control group was eliminated altogether. Choosing to eliminate them because they did not support the hypothesis would result biased results.

• They tested several hypotheses at once, but focused on the (possibly false) positive results.

• Of the low-functioning patients, only those whose relatives were involved enough to return the consent form were included. This is not a representative population.

• Choosing to sing is associated with having a high-functioning (good) day. High-functioning days leads to higher scores on the tests. Therefore, the choosing to sing, not the singing itself, could be the factor influencing the scores.