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Stats Exam 1
Baylor STA 3381 Exam 1-Dr. Young
27
Mathematics
Undergraduate 3
05/08/2014

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Term
The width of the confidence interval for the population mean depends on
Definition
the sample standard deviation
Term
The chief distinction between a point estimate and an interval estimate is that
Definition
an interval estimate indicates the precision of the estimate while a point estimate does not
Term
A 95 percent confidence interval for the mean time taken to process new insurancepolicies (in days) is 11 <= u <= 12. This interval can be interpreted to mean that
Definition
about 95 out of every 100 such intervals constructed from random samples of the same size will contain the population mean processing time
Term
An analyst, using a random sample of n = 500 families, obtained a 90 percent confidence interval for mean monthly family income for this large population: $600 <= u <= $800. If the analyst had used a 99 percent confidence coefficient instead, the confidence interval would be:
Definition
wider and would involve a smaller risk of being incorrect
Term
In constructing a confidence interval for the population mean, which of the following factors affect the width of the interval?
Definition
the variability in the population
Term
The sampling distribution of any statistic:
Definition
is a probability distribution of the possible different values that the sample statistic may take on
Term
The process of making decisions about the values of population parameters based on sample data is known as:
Definition
statistical inference
Term
Which statements apply to normal probability distributions?
Definition
They are all unimodal, they are all symmetric, and the area under the distribution is always 1.00
Term
The sampling distribution of X bar refers to:
Definition
the distribution of the different possible values of the sample mean together
Term
The characteristics (parameters) of the sampling distribution of X bar are materially affected by:
Definition
the sample size, the variability in the population, and the mean of the population
Term
The Central Limit Theorem assures us that the sampling distribution of the sample mean:
Definition
Is always approximately normal for sufficiently large sample sizes
Term
The standard error of the sample mean for a sample size of n = 2 or more is:
Definition
always less than the standard deviation of the population
Term
The Central Limit Theorem:
Definition
permits us to know the sampling distribution of the sample mean and, therefore, to know how accurate the sample mean is as an estimator of the population mean
Term
A simple random sample of a population is chosen in such a way that:
Definition
each possible sample combination has an equal probability of being chosen
Term
Simple random sampling refers to:
Definition
the method of sample selection
Term
The expected value of the sample mean, X bar, is the same as ______.
Definition
the population mean of the sample population
Term
The Central Limit Theorem is important because it can always be applied without assuming the distribution of the population of interest, provided the sample size is sufficiently ______ and the population variance is _____.
Definition
large; finite
Term
3 Types of Inference:
Definition
1) Point Estimation
2) Interval Estimation
3) Hypothesis Testing
Term
Point Estimation
Definition
estimates an unknown value with a single point
Term
Interval Estimation
Definition
-Gives a range of values that one believes could contain the correct value
-Catch parameter in an interval, accounts for uncertainty
Term
A random sample is NOT a representative sample, however, a:
Definition
random sample has a high chance of being a representative sample
Term
Parameters
Definition
describe the characteristic of the population (or random variable) or interest
Term
Every estimator of a population parameter is a random variable that has its own _______.
Definition
density function
Term
Every estimator is a ______.
Definition
statistic
Term
The purpose of statistical data analysis:
Definition
is to turn raw data into info one can use to make better decisions
Term
The standard normal distribution always has a mean equal to ___ and standard deviation equal to ____.
Definition
0; 1
Term
________ is a source of error for every estimator.
Definition
Sampling error
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