Ch.8 Business Stats – Flashcards
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difference between a point estimate and a confidence interval estimate
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a point estimate is a single point whereas a confidence interval is an interval estimate.
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construct and interpret a confidence interval estimate for a single population mean using both z and t distribution.
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use z distribution for population mean known by using the z distribution table and the knowledge of the standard error within such as within 1.96 then it's equal to .4750 and P(-1.96<=z<=1.96) = 0.4750+.4750=.95. use t distribution when population mean is unknown via the t distribution table.
use t-distribution when population mean is unknown base on degrees of freedom (n-1). use the t-table to determine the critical value when the population standard deviation is unknown.
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determine the required sample size to estimate a single population mean within a specified margin of error
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it must be >30 at least
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form and interpret a confidence interval estimate for a single population proportion
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figure out if population mean is unknown and then use either z or t distribtion along with their respected tables.
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Point Estimates
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is a single point percentage
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Interval Estimates
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an interval where the e value of a parameter of a population has a stated measured likelihood of happening.
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Confidence Level
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an interval estimate
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Finding the Critical Value
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point on the test distribution that is compared to the test statistic to determine whether to reject the null hypothesis.
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Margin of Error
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the amount added and subtracted to the point estimate to form the confidence interval.
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Student t Distribution and Degrees of Freedom
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t distribution: t-distribution table is used when population mean is unknown and specific t-distribution is chosen based on its degrees of freedom which is n-1 where n=sample size.
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A point estimate is a range of values used to estimate a population parameter
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FALSE
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An interval estimate is a single value used to estimate a population parameter.
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FALSE
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An interval estimate is a range of values used to estimate a population parameter.
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TRUE
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The higher the degree of confidence, the larger the sample required to give a certain precision
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TRUE
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For a given confidence interval what is the interpretation of a 96% confidence interval
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Approximately 96 out of 100 such intervals would include the true value of the population parameter.
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Which statement (s) is/are correct about the t distribution
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A. Mean = 0
B. Symmetric
C. Based on degrees of freedom
(ALL OF THEM)
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In sampling, what is not necessary to determine the number of individuals to select from a population?
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Size of the population.
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When a confidence interval for a population mean is constructed from sample data,
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we can conclude, with a stated level of confidence, that the population mean is in the interval.
