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QUANTITATIVE RESEARCH TECHNIQUES +
STATISTICS PEREGRINE; Actual exam with
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answers |excellent scores
A company developed a smartphone whose average lifetime is unknown. In order to estimate the average, 200 smartphones are randomly selected from a large production line and tested; their average is found to be 5 years. The 200 smartphones represent: - Correct-answer- a sample
Significance level - Correct-answer- Measures the reliability of a statistical inference
unbiased estimator - Correct-answer- a sample statistic which has an expected value equal to the value of the population parameter
Suppose a population of blue whales is 8000. Researchers are able to garnish a sample of oceanic movements from 100 blue whales within the population. Thus,
- researchers do not have a significant sample size
- researchers need a larger population of blue whales
- the finite population correction factor is necessary
- researchers can ignore the finite population correction factor - Correct-answer- researchers can ignore the finite population correction factor
In a sample proportion, represented by p = x/n, what does X refer to? - Correct-answer- # of successes in the sample
The branches in a decision tree are equivalent to - Correct-answer- events and acts
What is needed to compute posterior probabilities? - Correct-answer- The sum of all the P(sj and li)'s, likelihood probabilities, p (li/sj)
the standard error of the sample mean - Correct-answer- standard deviation of the distribution of the sample means , Standard deviation/sq rt (population size)
Business Statistics - Correct-answer- the collection, summarization, analysis, and reporting of numerical findings relevant to a business decision or situation
descriptive statistics - Correct-answer- uses graphical or numerical techniques to summarize and present data
mean - Correct-answer- average
measure of variability - Correct-answer- how closely scores bunch up around the central point; a statistic that indicates the spread of distribution
range - Correct-answer- the difference between the highest and lowest scores in a distribution
Median - Correct-answer- the middle score in a distribution; half the scores are above it and half are below it
Mode - Correct-answer- the most frequently occurring score(s) in a distribution
Variance - Correct-answer- the average of the squared deviations from the mean
standard deviation - Correct-answer- the square root of the variance and provides a measure of the standard, or average, distance from the mean
simple random sampling - Correct-answer- A sampling procedure in which each member of the population has an equal probability of being included in the sample. (example - tickets in a bin each assigned a number)
stratified random sampling - Correct-answer- obtained by separating the population into mutually exclusive sets of data (strata) then drawing a simple random sample from each stratum
cluster sampling - Correct-answer- random sample of the groups or clusters of elements versus a simple random sample of individual objects
Probability of any outcome must be between - Correct-answer- 0 and 1
Sum of all probabilities must equal: ____ - Correct-answer- 1
inferential statistics - Correct-answer- Process of using sample statistics (mathematics) to draw conclusions about population parameters
mutually exclusive - Correct-answer- Events that cannot occur at the same time.
sampling error - Correct-answer- the difference between the results of random samples taken at the same time
non-sampling error - Correct-answer- occurs when the sample data are incorrectly collected, recorded, or analyzed. Three types of errors: data acquisition errors, non-response errors (or bias), selection bias
Design of a good survey components - Correct-answer- short survey, short/simple questions, start with demographic questions, ues dichtomous (yes-no) and multiple choice
Direct observation - Correct-answer- example: counts backpacks on campus for a day
Conditional Probability - Correct-answer- the likelihood that a target behavior will occur in a given circumstance
Bayes Law - Correct-answer- calculates posterior probability
exhaustive - Correct-answer- including everything possible; very thorough or complete
Central Limit Theorem (CLT) - Correct-answer- The name of the theorem stating that the sampling distribution of a statistic (e.g. x ) is approximately normal whenever the sample is large and random. Allows us to draw conclusions about the population based on strictly sample data.
sampling distribution of the mean - Correct-answer- 1. the sampling distribution of the mean has a different mean from the original population
- the standard deviation of the sampling distribution of the mean is referred to as the standard deviation
- if the original population is not normally distributed, the sampling of the mean will be normal
Suppose you are given 3 numbers that relate to the number of people in a sample. The three numbers are 10, 20 and 30. If the standard deviation is 10, the standard error equals - Correct-answer- 5.
To find the standard deviation, find the mean of the data set ( 10, 20,
- then calculate in excel. Watch video Bozeman Science Standard Error
Find the sample standard deviation of 5, 10, 15 and 20. - Correct- answer- 6.
standard deviation - Correct-answer- a computed measure of how much scores vary around the mean score
one-tailed test - Correct-answer- A hypothesis test in which rejection of the null hypothesis occurs for values of the test statistic in one tail of its sampling distribution.
Three approaches to assigning probability - Correct-answer- classical approach, relative frequency approach, subjective approach
Classical Approach to Probability - Correct-answer- associated with games of chance. If an experiment has N possible outcomes, this method would assign probability of 1/n to each customer. For example, the probability of a heads and tails in the flip of a coin are equal to each other. Because the sum must be 1, the probability is 1/2, or 1/6 for a dice.
relative frequency approach to probability - Correct-answer- defines probability as the long run frequency in which something occurs. Example: the last 1000 students took a course, 200 got an A. The relative frequency is 20% - estimate of students that will get an A
subjective approach to probability - Correct-answer- the probability is obtained on the basis of personal judgement; often the only method of assigning likelihood to an outcome; educated guess based on knowledge available
union of two events - Correct-answer- Given by the outcomes that belong either to one or to both events.
calculate conditional Probability - Correct-answer- P (A1/B2)
Complement Probability - Correct-answer- event that occurs when A does not occur. P(A) + P(Ac) = 1
multiplication rule - Correct-answer- To determine the probability, we multiply the probability of one event by the probability of another.
