Test 2 Notes
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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| What is a Statistical Inference? | A procedure by which we use information from a sample, that is drawn from a population, to reach a conclusion about the population.
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| What is Estimation? | Estimation uses sample data to calculate a statistic that is an approximation of the parameter of the population from which the sample was drawn.
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| What is Samples Population? | The population from which you draw your sample.
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| What is Target Population? | The population you wish to make an inference about; the population you wish to generalize your results to.
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| Why is Estimation useful? | Workers in the health sciences field are often interested in parameters, such as proportions or means, of different populations.It is usually not feasible (due to cost and/or time limitations) to sample the entire population even if it is finite.
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| A ___________ is a single numerical value used to estimate the corresponding population parameter | Point estimate
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| An ___________ consists of a range of values (with a lower and upper bound) constructed to have a specific probability (the confidence) of including the population parameter. | Interval Estimate
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| An __________ is the single value computed. The __________ is the rule that that tells us how to compute the estimate | estimate, estimator
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| An estimate, T, is said to be an _______ of a parameter 0 if the expected value of the estimate (T) equals 0. E(T) = 0 | unbiased estimator
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| One criteria for picking the best estimator is the property of what? | Unbiasedness
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| Unbiased estimates of their corresponding parameters: | difference between two sample means, sample proportion, difference between two sample proportions
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| What is this:In repeated sampling from a normally distributed population with a known standard deviation, 100(1-α) percent of all intervals of the form will in the long run include the population mean mue | Probabilistic Interpretation
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| Unbiased estimates of their corresponding parameters: | difference between two sample means, sample proportion, difference between two sample proportions
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| What is this:In repeated sampling from a normally distributed population with a known standard deviation, 100(1-α) percent of all intervals of the form will in the long run include the population mean mue | Probabilistic Interpretation
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| What is this:When sampling is from a normally distributed population with a known standard deviation, we are 100(1-α) percent confident that the single computed interval, contains the population mean mue. | Practical Interpretaion
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| The ______________ is the quantity obtained by multiplying the reliability coefficient by the standard error of the mean. This quantity is also called the _______________ . | precision of the estimate, margin of error
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| You cannot always assume the population is normally distribution. However, the ________ tells us that for large samples, the sampling dist. of xbar is approximately normally distributed regardless of the distribution of the individuals in the population. | Central Limit Theorem
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| It is almost always the case that if you don’t know your population mean, u, (which is why we would use this estimation procedure), then you also don’t know your ______________ . | population variance
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| The number of ________ for a statistic equals the number of observations minus the number of components in its calculation that need to be estimated. | degrees of freedom (df)
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| How do you know if the population variances are equal? | If the larger samp.variance is more than 2x as lrg as the smlr samp. var.– then the pop. var. are un=. You don't have to use the un= var. form, for the CI around the dif. between 2 pop.means – if you encounter a ? that has unequal var.–var. are un= and th
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| n*p > 5 and n*(1-p) > 5, we can consider the sampling distribution of p-hat to be close to the ______________. | normal distribution
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| True or False If we fail to reject the null hypothesis then we conclude that the null hypothesis is true. | False
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| In a hypothesis test, one way to reject the null hypothesis is to see if the p-value is less than or equal to ________. | Aplha
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| When estimating the population mean, we use the ____distribution when the population variance is known and the _____ distribution when the population variance is unknown. | z, t
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| The ______gives us the probability associated with obtaining the computed test statistic or one more extreme if the null hypothesis is true. | p-value
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| Ture or FalseHolding everything else constant, a 99% confidence interval is wider than a 95% confidence interval. | True
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| The probability of rejecting a null when it is actually true is called _______; this is a Type ___ error. | aplha, Type 1
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| As the sample size ________ the standard error of the estimate decreases. | increases
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| True or FalseWhen evaluating a given hypothesis, a confidence interval and hypothesis test on the same data won't always give you the same conclusion. | True
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| The ____ hypothesis is always a statement of equality. | Null
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| Power is the term for the probability of: | Rejecting a null hypothesis when it is actually false.
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| True or False Using the same data, a p-value from a two tailed test is larger than a p-value based on a one-tailed test. | True
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| Holding everything else constant, as the sample size increases, the width of the confidence interval: | Decreases
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| What is the general form of a CI__________+/-________________*____________ _____________________________ | estimator+/-reliability coefficient/standard errorMargin of error
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| When calculating a confidence interval for the population mean and the population variance is unknown you use ____________ table. | t
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| What can we assume when p<aplha | That the variences are unequal and reject the null
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| What can we assume when p>aplha | That the variences are equal and fail to reject the null
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| When you see an equal sign what can you assume? | That it is a two tailed test and that to find the p-value you would have to divide by 2
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| When you see a greater than or less than sign what can you assume? | That the table is a one tailed test.
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