##### Chapter 7-13 Vocab
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#### Complete list of Terms and Definitions for Chapter 7-13 Vocab

Terms Definitions
continuous random variable that takes all values in some interval of numbers.
Sampling Distribution distribution of values taken by the statistic in all possible samples of the same size from the same population.
goodness of fit test used to help determine whether a population has a certain hypothesized distribution, expressed as proportions of population members falling into various outcome categories.
variance the average squared differences of the values of the variable from their mean.
chisquare statistic measure of how far the observed counts in a two-way table are from the expected counts.
test of significance asseses the evidence provided by data against a null hypothesis in favor of the alternative hypothesis.
Discrete random variable that has a countable number of possible values.
Matched Pair Design in which a before and after of the same subjects are compared., A matched pairs design compares exactly two treatments, either by using a series of individuals that are closely matched two by two or by using each individual twice.
independent when the result of one observation tells you nothing about the other observations.
random variable a variable whose value is a numerical outcome of a random phenomenom.
Central limit theorem stating that the sum of a number of random variables obeying certain conditions will assume a normal distribution as the number of variable becomes large
mean the balance point of the probability histogram or density curve.
type I error that occurs if we reject Ho when it is in fact true.
exponential distribution with mean and standard deviation equal to one.
geometric distribution used when the number of trials is unknown.
probability histogram compares the probability model for random digits with the model given by Benford's Law.
expected count (in any cell of a two-way table when the null hypothesis is true) row total times column total over table total.
confidence interval uses sample data to estimate an unknown population parameter with an indication of how accurate the estimate is and of how confident we are that the result is correct.
cumulative distribution function calculates the sum of the probabilities for 0,1,2,...... up to value X.
type II error that occurs if we accept Ho when in fact Ha is true.
expected value mean of a random variable
variability the spread of a statistic's sampling distribution.
standard deviation square root of variance. measures the variability of the distribution about the mean.
law of large numbers the average of the values of x observed in many trials must approach ?.
Z Statistic used when the population standard deviation is known or used when dealing with proportions.
expected count obtained by multiplying the proportion of the distribution for each category times the sample size.
chi square a family of distributions that take only positive values and are skewed to the right.
normal distribution one type of continuous probability distribution.
sample a selected representation of the population.
parameter a number that describes a population.
p-value probability, computed supposing Ho to be true, that the test statistic will take a value at least as extreme as that actually observed.
binomial distribution that requires a fixed number of trials
unbiased statistics the mean of its sampling distribution is equal to the true value of the parameter being estimated.
degrees of freedom sample size minus 1.
degrees of freedom one parameter which specifies a specific chi square distribution.
probability distribution lists the values and their probabilities; described by a density curve.
confidence level states the probability that the method will give a correct answer.
bias Any variable that can alter the center of a data set, or alter the outcomes.
standard error the result when the standard deviation of a statistic is estimated from the data.
Probability distribution function assigns a probability to each value of X.
density curve describes the probability distribution of a continuous random variable.
power measures a significant test's ability to detect an alternative hypothesis.
statistic a number that can be computed from the sample data.
alternative hypothesis that proposes a change or opposes the claimed hypothesis.
Least-squares regression fits a straight line through data in order to predict a response variable Y from the explanatory variable X.
statistical inference provides methods for drawing conclusions about a population from sample data.
null hypothesis that says there is no effect or change in the population.
probability model overall description of the population.