Stats (inferrential statisitics/ tests) Flashcards
An inferential statistical test enables an investigator to determine the probability of obtaining a sample with a particular value by comparing the obtained sample value to an appropriate _______ distribution
sampling
when the sample value of interest is a mean, the comparison distribution is the sampling distribution of the ______, which is the distribution of means that would be obtained if a large number of equal-sized random samples were drawn from the same _______ and the mean of each sample was calculated
mean; population
while many sample means would equal the population mean, because of the effects of ______ some means would be lower than the population mean and some would be higher
sampling error
In inferential statistics, a sampling distribution is not actually constructed by obtaining a large number of samples. Instead, a theoretical sampling distribution is derrived from probability theory. According to the ______ Theorem, the sampling distribution of the mean is _______ shaped; its mean equals the ______; and its standard deviation, the ______ of the mean, is equal to the population _______ divided by the square root of the __________
central limit; normally; population mean; standard error; standard deviation; sample size (N)
hypothesis testing involves first translating the verbal research hypothesis into two competing statistical hypotheses: The ______ hypothesis is stated in a way that implies that the independent variable does not have an effect on the dependent variable and that any observed effect is the result of _______
null; sampling error
The _______ hypothesis states the opposite of the null hypothesis and is expressed in a way that implies that the independent variable does ________ the dependent variable
alternative; have an effect on
the alternative hypothesis can take one of two forms: A _______ alternative hypothesis predicts whether the population value will be greater or _____ the population value specified in the null hyposthesis; while a ________ alternative hypothesis states only that the population value is not equal to the value stated in the null hypothesis
directional; less than; nondirectional
the results of an inferential statistical test indicate whether the obtained sample value falls within the region of likely or unlikely values in the _______ distribution
sampling
when the results of the statistical test indicate that the obtained sample value falls in the region of unlikely values, the null hypothesis is ______ and the alternative hypothesis is _______
rejected; retained
when the results indicate that the sample value falls in the region of likely values, the null hypothesis is _____ and the alternative hypothesis is _______
retained; rejected
the size of the ______ region (region of unlikely values) is defined by alpha. A researcher sets alpha before collecting or analyzing the data.
rejection
in psychological research, alpha is usually set at .01 or _______
.05
when alpha is .01, this means that _____% of the sampling distribution is the region of unlikely values, while the remaining ___% is the region of likely values
1; 99
the region of unlikely values is always placed in one or both ______ of the sampling distribution so that it contains the sample values that are least likely to occur as the result of sampling error alone
tails
when the results of a study are statistically ______, this means that the obtained sample value is in the _____ of the sampling distribution and that the investigator has rejected the ______
significant; rejection region; null hypothesis
when a researcher makes a decision to retain or reject the ______ hypothesis, there is no way to know with certainty if the decision is correct or in error
null
there are two kinds of decision errors: Type 1 error is made when a true null hypothesis is ________. This occurs when a researcher concludes that the independent variable has had an effect on the dependent variable, but the observed effect was actually due to _______
rejected; sampling error
the probability of making a Type 1 error is equal to _____
alpha (level of significance)
when _____ is set at .05 and the researcher has rejected the null hypothesis, there is a ___% chance that a Type 1 error has been made
alpha; 5
a Type II error is made when a false null hypothesis is ______. This occurs when the researcher decides that an independent variable has had no effect on the dependent variable when it actually did
retained
a Type II error might occur when ______ variable was not administered in sufficient intensity or for a long enough period of time, when the sample size was too _____, or when alpha is too ______
independent; small; small
a researcher can, of course, make a correct decision. One kind of correct decision is to _______ a true null hypothesis. In this situation, the researcher correctly concludes that any observed effect of an IV is actually due to ________
retain; sampling error
the other correct decision is to ______ a false null hypothesis. In this situation, the researcher correctly decides that the ______ had an effect on the DV
reject; IV
statistical power is increased as alpha ______, as the sample size ____, and as the magnitude of the effect of the independent variable increases
increases; increases