# Shared Flashcard Set

## Details

Statistics Ch. 7-8
Confidence Intervals, Hypothesis Testing etc
15
Mathematics
10/25/2009

Term
 Confidence Interval
Definition
 the interval to be constructed that specifies the range of values that we are relatively confidents the population mean falls within; stated in terms of a probability or percentage; the one used most commonly by researchers in behavioral sciences is the 95% confidence interval
Term
 Confidence Limits
Definition
 define the boundaries of the confidence interval
Term
 Confidence Interval when the standard deviation of a sampling distribution is known
Definition
 uses z-scores; uses the standard normal distribution as a model;
Term
 Confidence Intervals when the standard deviation of a sample distribution is unknown
Definition
 uses the t-distribution; used also because the standard normal distribution is not always the best model
Term
 When is the standard normal distribution a good fit?
Definition
 a. when N is sufficiently large b. when the scores are randomly selected from a population that is normally distributed
Term
 When does a t-distribution provide a better model than does the standard normal distribution?
Definition
 when o` is unknown; which is virtually always
Term
 Degrees of Freedom
Definition
 the number of independent pieces of information needed to determine a statistic; (N-1)
Term
 Two Goals of Inferential Statistics
Definition
 1. make unbiased estimates 2. assess error made when making estimates
Term
 Standard Error
Definition
 the standard deviation of a sampling distribution
Term
 Standard Error of the Mean
Definition
 the standard deviation of a sampling distribution for an estimate of the mean
Term
 How can we calculate unbiased estimators of o`2 and o`?
Definition
 by dividing SS by its degrees of freedom
Term
 S tends to __________ o`
Definition
 underestimate; thus it is an unbiased estimator
Term
 So how do we get an unbiased estimator of o`?
Definition
 By dividing SS by its degrees of freedom (n-1)
Term
 What does the standard error of the mean estimate?
Definition
 It estimates the typical amount of error made when using X` to estimate u
Term
 The greater the absolute value of the hypothesis testing statistic...
Definition
 the greater the size of the apparent effect relative to sampling error
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