Chapter 1 Introduction to Statistics
Statistical Significance versus Practical significance: What is the difference between
statistical significance and practical significance? Can a statistical study have
statistical significance, but not practical significance? - ANSWER-(A)Statistical
significance is indicated when methods of statistics are used to reach a conclusion
that some treatment or finding is effective, but common sense might suggest that
the treatment or finding does not make enough of a difference to justify its use or to
be practical. Yes, it is possible for a study to have statistical significance but not
practical significance.
Source of data: In concluding a statistical study, why is it important to consider the
source of the data? - ANSWER-(A) It's important to determine if the source of the
data would be impacted favorably by the conclusions of the data. If so the
conclusion is likely bias and invalid.
Voluntary Response Sample:What is a voluntary response sample, and why is such a
sample generally not suitable for a statistical study? - ANSWER-(A) A voluntary
response sample is a sample in which the subjects themselves decide whether to be
included in the study. A voluntary response sample is generally not suitable for a
statistical study because the sample may have a bias resulting from participation by
those with a special interest in the topic being studied.
Correlation and Causation: What is meant by the statement that "correlation does
not imply causation"? - ANSWER-(A) Correlation is an association between two
variables. For example, a statistical study may justify the statement that there is a
correlation between the number of cigarettes smoked and pulse rate, but it would
not justify a statement that the number of cigarettes smoked causes a person's pulse
rate to change. Statements about causality can be justified by physical evidence, not
by statistical analysis.
, Determine if results have statistical and practical significance: In a study of the
Marisa Waite diet, four subjects lost an average of 45 pounds. It is found that there
is about a 30% chance of getting such results with a diet that has no effect. -
ANSWER-Because there is a 30% chance of getting such results with a diet that has
no effect, it does not appear to have a statistical significance, but the average loss of
45 pounds does appear to have practical significance.
Determine if results have statistical and practical significance: In a study of the
Gender Aide method of gender selection, 1000 user of the method gave birth to 540
boys and 460 girls. There is about a 1% chance that such extreme results would
occur if the method had no effect. - ANSWER-Because there is a 1% chance that such
results would occur if the method had no effect, is appears to have statistical
significance, but it does not appear to have practical significance.
When making random guesses for difficult multiple-choice test questions with
possible answers of a, b, c, d, and e, we expect to get about 20% of the answers
correct. The Ashton Prep Program claims to have developed a better method of
guessing. In a test of that program, guesses were made for 100 answers, and 23
were found to be correct. There is a 23% chance of getting such results if the
program has no effect. - ANSWER-Because there is a 23% chance of getting such
results if the program has no effect, it does not appear to have statistical significance.
Because the success rate of 23% is not that much better than the 20% rate, it does
not appear to have practical significance.
Most people have IQ scores between 70 and 130. For $32, you can purchase a
computer program from Highiqpro.com that is claimed to increase your IQ score by
10 to 20 points. The program claims to be "the only proven IQ increasing software in
the brain training market," but the author of your text could find no data supporting
that claim, so let's suppose that these results were obtained: In a study of 12
subjects using the program, the average increase in IQ is 3 IQ points. There is a 25%
chance of getting such results if the program has no effect. - ANSWER-Because there
Statistical Significance versus Practical significance: What is the difference between
statistical significance and practical significance? Can a statistical study have
statistical significance, but not practical significance? - ANSWER-(A)Statistical
significance is indicated when methods of statistics are used to reach a conclusion
that some treatment or finding is effective, but common sense might suggest that
the treatment or finding does not make enough of a difference to justify its use or to
be practical. Yes, it is possible for a study to have statistical significance but not
practical significance.
Source of data: In concluding a statistical study, why is it important to consider the
source of the data? - ANSWER-(A) It's important to determine if the source of the
data would be impacted favorably by the conclusions of the data. If so the
conclusion is likely bias and invalid.
Voluntary Response Sample:What is a voluntary response sample, and why is such a
sample generally not suitable for a statistical study? - ANSWER-(A) A voluntary
response sample is a sample in which the subjects themselves decide whether to be
included in the study. A voluntary response sample is generally not suitable for a
statistical study because the sample may have a bias resulting from participation by
those with a special interest in the topic being studied.
Correlation and Causation: What is meant by the statement that "correlation does
not imply causation"? - ANSWER-(A) Correlation is an association between two
variables. For example, a statistical study may justify the statement that there is a
correlation between the number of cigarettes smoked and pulse rate, but it would
not justify a statement that the number of cigarettes smoked causes a person's pulse
rate to change. Statements about causality can be justified by physical evidence, not
by statistical analysis.
, Determine if results have statistical and practical significance: In a study of the
Marisa Waite diet, four subjects lost an average of 45 pounds. It is found that there
is about a 30% chance of getting such results with a diet that has no effect. -
ANSWER-Because there is a 30% chance of getting such results with a diet that has
no effect, it does not appear to have a statistical significance, but the average loss of
45 pounds does appear to have practical significance.
Determine if results have statistical and practical significance: In a study of the
Gender Aide method of gender selection, 1000 user of the method gave birth to 540
boys and 460 girls. There is about a 1% chance that such extreme results would
occur if the method had no effect. - ANSWER-Because there is a 1% chance that such
results would occur if the method had no effect, is appears to have statistical
significance, but it does not appear to have practical significance.
When making random guesses for difficult multiple-choice test questions with
possible answers of a, b, c, d, and e, we expect to get about 20% of the answers
correct. The Ashton Prep Program claims to have developed a better method of
guessing. In a test of that program, guesses were made for 100 answers, and 23
were found to be correct. There is a 23% chance of getting such results if the
program has no effect. - ANSWER-Because there is a 23% chance of getting such
results if the program has no effect, it does not appear to have statistical significance.
Because the success rate of 23% is not that much better than the 20% rate, it does
not appear to have practical significance.
Most people have IQ scores between 70 and 130. For $32, you can purchase a
computer program from Highiqpro.com that is claimed to increase your IQ score by
10 to 20 points. The program claims to be "the only proven IQ increasing software in
the brain training market," but the author of your text could find no data supporting
that claim, so let's suppose that these results were obtained: In a study of 12
subjects using the program, the average increase in IQ is 3 IQ points. There is a 25%
chance of getting such results if the program has no effect. - ANSWER-Because there
