STAT 211 Module 9 HW Quiz Final
When testing a new treatment, what is the difference between statistical significance and practical
significance? Can a treatment have statistical significance, but not practical significance?
Statistical
significance is achieved when the result is very unlikely to occur by chance. Practical significance is
related to whether common sense suggests that the treatment makes enough of a difference to justify
its use. It is possible for a treatment to have statistical significance, but not practical significance.
What is the goal of statistics?
To learn to distinguish between statistical conclusions that are likely to be
valid and those that are seriously flawed.
Determine whether the underlined number is a statistic or a parameter. A sample of employees is
selected and it is found that 40%
own a vehicle.
Statistic because the value is a numerical measurement
describing a characteristic of a sample.
Determine which of the four levels of measurement (nominal, ordinal, interval, ratio) is most appropriate
for the data below. Diameter of circles in inches.
The ratio level of measurement is most appropriate
because the data can be ordered, differences (obtained by subtraction) can be found and are
meaningful and there is a natural starting zero point.
Identify the type of sampling used (random, systematic, convenience, stratified, or cluster sampling) in
the situation described below. In a poll conducted by a certain research center, 1081 adults were called
after their telephone numbers were randomly generated by a computer, and 38% were able to correctly

Among fatal plane crashes that occurred during the past 70 years, 408 were due to pilot error, 60 were
due to other human error, 605 were due to weather, 106 were due to mechanical problems, and 119
were due to sabotage. Construct the relative frequency distribution. What is the most serious threat to

46.6%, Mechanical problems 8.2%, Sabotage 9.2%. Weather is the most serious threat to aviation
safety. Weather monitoring systems could be improved.
Natural births randomly selected from four hospitals in a highly populated region occurred on the days
of the week (in the order of Monday through Sunday) with the frequencies 53, 63, 72, 59, 57, 43, 53.
Does it appear that such births occur on the days of the week with equal frequency?
Monday 13.25%,
Tuesday 15.75%, Wednesday 18%, Thursday 14.75%, Friday 14.25%, Saturday 10.75%, Sunday 13.25%.

Heights of adult males are normally distributed. If a large sample of heights of adult males is randomly