answer to a question.

[dolly123]

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Hi,
Need an answer to the following questions.
Q: a hepatitis B virus antibody positive person is one who can

contact HBV Transmit HBV
a. yes yes
b. no yes
c.yes no
d.no no.


Q: a cross over research design functions to

a.minimize bias
b.reduce relapse
c.facilitate statistical analysis
d.eliminate blindness in the recorder.

please help me with the answer to my questions.also where can i get more info for the second question.

Thank you all.

 

[toothie]

Hi,
Need an answer to the following questions.
Q: a hepatitis B virus antibody positive person is one who can

contact HBV Transmit HBV
a. yes yes
b. no yes
c.yes no
d.no no.


im presuming u mean a person who has antibodies to Hepatitis B is one who can Contact or transmit HBV.
answer is D.
if a person has antibodies... he cannot contact or transmit HBV

 

[toothie]

Case-Control Studies
Advantages:
quick and cheap;
only feasible method for very rare disorders or those with long lag between exposure and outcome;
fewer subjects needed than cross-sectional studies.
Disadvantages:
reliance on recall or records to determine exposure status;
confounders;
selection of control groups is difficult;
potential bias: recall, selection.


Cross-Sectional Survey
Advantages:
cheap and simple;
ethically safe;.
Disadvantages:
establishes association at most, not causality;
recall bias susceptibility;
confounders may be unequally distributed;
Neyman bias;
group sizes may be unequal.

Cohort Study
Advantages:
ethically safe;
subjects can be matched;
can establish timing and directionality of events;
eligibility criteria and outcome assessments can be standardised;
administratively easier and cheaper than RCT.
Disadvantages:
thcontrols may be difficult to identify;
exposure may be linked to a hidden confounder;
blinding is difficult;
randomisation not present;
for rare disease, large sample sizes or long follow-up necessary.

Randomised Controlled Trial
Advantages:
unbiased distribution of confounders;
blinding more likely;
randomisation facilitates statistical analysis.
Disadvantages:
expensive: time and money;
volunteer bias;
ethically problematic at times.

Crossover Design
Advantages:
all subjects serve as own controls and error variance is reduced thus reducing sample size needed;
all subjects receive treatment (at least some of the time);
statistical tests assumeing randomisation can be used;
blinding can be maintained.
Disadvantages:
all subjects receive plcebo or alternative treatment at some point;
washout period lengthy or unknown;
cannot be used for treatments with permanent effects.

 

[toothie]

Q: a cross over research design functions to

a.minimize bias
b.reduce relapse
c.facilitate statistical analysis
d.eliminate blindness in the recorder.

i think the answer is B

 

[dolly123]

Q: a cross over research design functions to

a.minimize bias
b.reduce relapse
c.facilitate statistical analysis
d.eliminate blindness in the recorder.

i think the answer is B

Thanks a lot Toothie.also if you can please tell me which book you refered for the answer to my 2'nd question.

Thank you.