Questions asked by Jill

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• What is the importance of descriptive statistics?
  
• What is the difference between a population and a sample?
  
• Why do statisticians use samples?
  
• What are some benefits of using a sample instead of a census?
  
• What is the difference between continuous data and discrete data?
  
• Give an example of each: continuous data and discrete data.
  
• How do the different measures of center compare?
  
• What is the difference between the sample mean and the population mean?
  
• How do you find the median of a set of values when there is an even number of values?
  
• What is the median for the following data set: 10 8 16 2
  
• What is the median for the following data set: 10 8 16 2 100
  
• We say that the median is a resistant measure, whereas the mean is not a resistant measure. What's a resistant measure?
  
• A course has 2 sections, Section A and Section B. On the last exam, Section A's 10 students had an average score of 80, and Section B's 20 students had an average score of 90. What is the course average score on that exam?
  
• A course has two sections, Section A and Section B. On the most recent exam, Section A's 10 students averaged 80, and Section B's 20 students averaged 90. What is the course average for this exam?
  
• Jane has scores of 84, 92, and 89 on her first 3 exams. What does she need to score on the next exam so that her overall average will be 90?
  
• The median is called a resistant measure, whereas the mean is a non-resistant measure. What's a resistant measure?
  
• The mean is the most-used measure of center, but there are times when it is recommended to use the median for data display and analysis. When might it be appropriate to use the median instead of the mean?
  
• Does a data set always have a mode?
  
• How do you make a bar chart?
  
• How do you find the central angle of a pie chart for a section of the pie chart that represents 20% of the pie?
  
• Under what conditions can you not use a pie chart to display categorical (qualitative) data?
  
• What is the difference between categorical (qualitative) data and numerical (quantitative) data?
  
• What is the special name for a bar chart that displays the bars' frequencies from greatest to least?
  
• Can the standard deviation be greater than the mean?
  
• Can the standard deviation ever be negative?
  
• What is the sample standard deviation formula?
  
• What is the symbol for the sample standard deviation?
  
• What are the symbols for the sample variance and for the population variance?
  
• Which data set has a larger standard deviation? First Data Set: 2, 4, 6, 8 Second Data Set: 12, 12, 12, 12
  
• If the standard deviation of a distribution is s = 7, what is its variance?
  
• Is the sample standard deviation "s" a resistant measure?
  
• How do you calculate the range of a data set?
  
• For the data set 6, 34, 12, and 14, what is the range?
  
• Why is the range of a data set seldom used in statistical analysis?
  
• Which of the following would be classified as categorical data? age, gender, height, letter grade on most recent exam, percentage correct on most recent exam, number of likes to a Facebook posting, weight, eye color, gas mileage of your car
  
• Two days before an election, city officials projected that 67% of all registered voters would vote. Two days after the election, after reviewing the actual voting turnout, they announced that 81% of registered voters had actually voted. Which of these percentages is a parameter, and which is a statistic?
  
• This dotplot summarizes total scores for beginning golfers on a 9-hole golf course. What are the mean, median, and mode of the scores?
  
• What are the two major advantages of both dotplots and stemplots?
  
• What is a bimodal graph?
  
• Is a bell curve symmetric, right-skewed, or left-skewed?
  
• You have final exam scores from two different sections of a Chemistry course and you want to compare them. What special type of stemplot will you use for this purpose?
  
• How do i find class midpoints?
  
• When do I use class boundaries?
  
• What are class limits?
  
• What must the frequencies in a frequency distribution add up to?
  
• How do you find the cumulative frequency in a frequency table?
  
• How do you find the cumulative relative frequency?
  
• What information does an ogive provide?
  
• How do I calculate the lower class boundary and the upper class boundary for the class 40 - 59?
  
• What is a relative frequency distribution?
  
• How can the bin width affect the shape of a histogram?
  
• How do you create a histogram from a frequency table?
  
• Why do the bars touch on a histogram but not on a bar chart?
  
• What is a bin in a histogram?
  
• If a histogram is unimodal and symmetric, what well-known curve will the histogram approximate?
  
• How can I create a histogram in Excel?
  
• How is Benford's Law used in detecting possible cheaters on income tax returns?
  
• If a person scores in the 45th percentile on the ACT, how do we interpret this?
  
• The third quartile, denoted #Q_3#, is the data value such that what percent of the values are below it?
  
• What percent of values of a data set are less than the median?
  
• What does a z score tell you?
  
• Anthony enters a fishing contest. After all the fish are measured, it is announced that the mean fish length was 13 inches, with a standard deviation of 4 inches. Anthony's biggest fish measured 19 inches. What is the z-score for his fish's length?
  
• Find the values of #Q_1#, #Q_2#, and #Q_3# for the following data values: 6, 8, 13, 15, 16, 16, 18
  
• Do box plots show outliers?
  
• What is another name for a boxplot?
  
• Is the median always in the exact middle of a boxplot?
  
• How would I find the 5-number summary for the data set: 54, 9, 37, 15, 52, 40, 54, 78, 1, 3, 26, 26, 37?
  
• How does the interquartile range relate to percentiles?
  
• What does the interquartile range tell us?
  
• What is a modified boxplot?
  
• How do you identify outliers when displaying data in a boxplot?
  
• If you were to add 5 to each value in a data set, what effect would this have on the standard deviation of the data set?
  
• If you were to multiply each value in a data set by 6, what effect would this have on the mean of the data set?
  
• If you were to multiply each value in a data set by 6, what effect would this have on the standard deviation of the data set?
  
• In a biology lab, a student has measured the lengths of 30 palmetto bugs in inches. He computes the mean and standard deviation as 4.1 inches and 1.2 inches, respectively. He later finds out that he was supposed to calculate the mean and standard deviation in centimeters instead of in inches. What are the new mean and standard deviation of his sample, in centimeters? (Note: 1 in = 2.54 cm)
  
• A professor's final exam has a mean of 60 and a standard deviation of 12. She decides that it was too difficult, so she adds 15 points to each student's score. Rather than recalculate the mean and standard deviation for the 442 scores, she remembers that she can use the linear transformation rules to recalculate the mean and standard deviation. What are the revised mean and standard deviation of her final exam?
  
• A meteorologist has recorded daily high temperatures for the last month, in degrees Centigrade, and he presents the mean of 21 degrees C. and standard deviation of 3 degrees C. during the evening news. While on camera, his co-anchor says that nobody understands degrees C, so he does an on-the-spot conversion of these two values to degrees Fahrenheit. What are the converted mean and standard deviation? (Note: F = (1.8)(C) + 32)
  
• How does a census differ from a sample?
  
• How do I take a simple random sample, using a TI-84?
  
• How do random samples and stratified samples differ?
  
• Is a stratified sample considered to be a simple random sample?
  
• How can systematic sampling be biased?
  
• How can convenience samples be biased?
  
• In what way are voluntary response samples often biased?
  
• How can a researcher avoid a biased sample?
  
• The draft lottery of 1969 was biased. What was the error made by the draft lottery statisticians?
  
• A random sample of 40 tea drinkers scores much lower on a stress scale than a random sample of those who do not drink tea. Does drinking tea lower stress?
  
• You weigh 30 people who exercise every day, and you weigh 30 people who do not get regular exercise. The exercise group has a mean weight which is 22 pounds less than the non-exercise group's mean. Can you conclude that exercise causes people to weigh less?
  
• How do you minimize response bias?
  
• What is non response bias?
  
• What are some basic guidelines concerning the design of a questionnaire?
  
• What is wrong with the answer choices to the question: How much did you like your statistics course this semester? (A.) Not at all (B.) A lot (C.) It was awesome!
  
• What is a control group?
  
• What is the purpose of a control group in an experiment?
  
• What is the purpose of blocking in some experiments?
  
• What is the purpose of a placebo group in an experiment?
  
• What is the goal of a matched pair design?
  
• What is the purpose of double blind experiments?
  
• How can an experiment show cause and effect?
  
• What is statistical significance?
  
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