PBSI 245 Exam 1 questions well
answered graded A+
A statistician tells the producer that the margin of error for a 95% confidence
statement for these data is about plus or minus 2 percentage points. The producer
therefore reports that between 2.8% and 6.8% (that's 4.8% +/- 2%) of all the bags
of spinach are contaminated. This isn't right: only 1% is contaminated. What went
wrong? - correct answer ✔✔A 95% confidence statement is only right for 95% of all possible
samples. This must be one of the 5% for which one gets an incorrect
conclusion.
Can pleasant aromas help people work more efficiently? Researchers did this study to find out.
Twenty-two students worked a paper-and-pencil maze six times. On three tries, they
wore a mask with floral scents. On the other three tries, they wore a mask with no scent. The six
tries were done in random order and each used a different maze. The researchers
found that the subjects took less time to complete the maze when wearing the scented mask.
This study is a(n): - correct answer ✔✔Experiment
Does St. John's wort have a significant effect in treating major depression? A study looked at
340 adult outpatients suffering from major depression as measured by their HAM-D
score, randomly assigning each subject to either a placebo, St. John's wort, or a second active
treatment for comparison.
The study found the difference in treating major depression as measured by improvement in
HAM-D scores between St. John's wort and the placebo was not statistically
significant. This means that: - correct answer ✔✔A difference this big could easily occur just by
chance
, A U.S. Census Bureau report on the income of Americans say with 90% confidence the median
income of all California households in 2007 was $67,484 with a margin of error of +/- $375. This
means that, - correct answer ✔✔The census bureau got the result $67,484 +/- $375 using a
message that will cover the true median income 90% of the time when used repeatedly
The essential difference between an experiment and an observational study is that - correct
answer ✔✔an experiment imposes treatments on the subjects, but an observational study does
not
The US population census is a census because we attempt to collect data from - correct answer
✔✔Every individual in the population
If the researchers are not blind to the assignment of the treatment groups they could bias the
experiment by - correct answer ✔✔All of the above
The report of the SAT study says with 95% confidence one can say that students who are
coached raise their average SAT scores by between 28 and 57 points more than students who
are not coached. By 95% confidence in the report means that - correct answer ✔✔The study
obtained the 28 to 57 point range by using a method that would give a correct answer at 95% of
all samples
Parameters describe population characteristics - correct answer ✔✔True
An ad for a new mouth rinse says that it reduces plaque on teeth by 200% what does this mean
- correct answer ✔✔It's nonsense because removing 100% of the plaque already removes all of
it, and you cannot remove more than there was at the beginning.
Voluntary response polls almost always suffer from - correct answer ✔✔high bias
In what kind of study is the environments of the subjects controlled or manipulated by the
researcher - correct answer ✔✔Experiment
answered graded A+
A statistician tells the producer that the margin of error for a 95% confidence
statement for these data is about plus or minus 2 percentage points. The producer
therefore reports that between 2.8% and 6.8% (that's 4.8% +/- 2%) of all the bags
of spinach are contaminated. This isn't right: only 1% is contaminated. What went
wrong? - correct answer ✔✔A 95% confidence statement is only right for 95% of all possible
samples. This must be one of the 5% for which one gets an incorrect
conclusion.
Can pleasant aromas help people work more efficiently? Researchers did this study to find out.
Twenty-two students worked a paper-and-pencil maze six times. On three tries, they
wore a mask with floral scents. On the other three tries, they wore a mask with no scent. The six
tries were done in random order and each used a different maze. The researchers
found that the subjects took less time to complete the maze when wearing the scented mask.
This study is a(n): - correct answer ✔✔Experiment
Does St. John's wort have a significant effect in treating major depression? A study looked at
340 adult outpatients suffering from major depression as measured by their HAM-D
score, randomly assigning each subject to either a placebo, St. John's wort, or a second active
treatment for comparison.
The study found the difference in treating major depression as measured by improvement in
HAM-D scores between St. John's wort and the placebo was not statistically
significant. This means that: - correct answer ✔✔A difference this big could easily occur just by
chance
, A U.S. Census Bureau report on the income of Americans say with 90% confidence the median
income of all California households in 2007 was $67,484 with a margin of error of +/- $375. This
means that, - correct answer ✔✔The census bureau got the result $67,484 +/- $375 using a
message that will cover the true median income 90% of the time when used repeatedly
The essential difference between an experiment and an observational study is that - correct
answer ✔✔an experiment imposes treatments on the subjects, but an observational study does
not
The US population census is a census because we attempt to collect data from - correct answer
✔✔Every individual in the population
If the researchers are not blind to the assignment of the treatment groups they could bias the
experiment by - correct answer ✔✔All of the above
The report of the SAT study says with 95% confidence one can say that students who are
coached raise their average SAT scores by between 28 and 57 points more than students who
are not coached. By 95% confidence in the report means that - correct answer ✔✔The study
obtained the 28 to 57 point range by using a method that would give a correct answer at 95% of
all samples
Parameters describe population characteristics - correct answer ✔✔True
An ad for a new mouth rinse says that it reduces plaque on teeth by 200% what does this mean
- correct answer ✔✔It's nonsense because removing 100% of the plaque already removes all of
it, and you cannot remove more than there was at the beginning.
Voluntary response polls almost always suffer from - correct answer ✔✔high bias
In what kind of study is the environments of the subjects controlled or manipulated by the
researcher - correct answer ✔✔Experiment
