Chapter 6 Statistics INTRO TO HYPOTHESIS TESTING

the z scores that are the critical values for a two-tailed, single-sample z test with the alpha set of .05 are ___ and ___.

-1.96; +1.96

nonrobust assumption

-has to be met for the test to proceed -if violated, a researcher should stop proceeding with the planned statistical test

Null hypothesis

-negative statement -makes a specific prediction -the null hypothesis says that in the population, the explanatory variable does NOT have an impact on the outcome variable -one cant prove a negative statement, but one can disprove a negative statement

alternative hypothesis

-usually, a statement of what the researcher believes to be true -a statement that the explanatory variable has an effect on the outcome variable in the population

6 steps of hypothesis testing*

1. pick the right statistical test 2. assumptions: check the assumptions to make sure its OK to do the test 3. hypotheses: list the null and alternative 4. decision rule: find the critical value of the statistic that determines when to reject the null hypothesis 5. calculation 6.interpretation

two-tailed tests are the norm and are used much more frequently than one-tailed tests

TRUE

unlike the null hypothesis, the alternative hypothesis DOESNT make a specific prediction

TRUE

Hypothesis

a proposed explanation for observed facts; a statement or prediction about a population value

the hypothesis a researcher believes is really true is the _____ hypothesis

alternative

if the _______ of a hypothesis test aren't met, one cant be sure what the results mean.

assumptions

robust assumption

can be violated, to some degree, and the test can still be completed and interpreted

Hypothesis' must be ALL-INCLUSIVE

covering all possible outcomes ex: if one hypothesis said "all cars are white," the other hypothesis would state "not all cars are white"

the decision rule involves finding the _________ of the test statistic.

critical value

it just takes one example to ______ a negative statement

disprove

two-tailed hypothesis test

doesnt indicate whether the explanatory variable has a positive or negative impact on the outcome variable, just that it has an impact

a hypothesis is a proposed _______ for observed ________.

explanation; facts

the first question to be addressed in an interpretation is whether one _____ the null hypothesis.

has rejected

if what is observed in a sample is close to what is expected of the hypothesis is true, there is little reason to question the

hypothesis

one-tailed hypothesis test

hypothesis that predicts the explanatory variable has an impact on the outcome variable in a SPECIFIC DIRECTION

a two tailed test has _______ hypothesis.

nondirectional

it is easier to reject the null hypothesis with a ___-tailed test than a ___-tailed test.

one;two

Hypothesis' must be MUTUALLY EXCLUSIVE

only one hypothesis at a time can be true

____, in APA format, means the null hypothesis was rejected.

p<.05

rare zone

part of the sampling distribution in which it is rare that a sample mean falls; typically, 5% of the sampling distribution

in order to use a single sample z test, one must know the ________ standard deviation&**

population

the null hypothesis for a single-sample z test says that the _____ is a specific value

population mean

the numerator in calculating a single-sample z test is the difference between the _____ and the _____.

sample mean; population mean

one shouldn't expect the sample mean to be exactly the same as the population mean because of ________

sampling error

if the result of a single sample z test is statistically significant, that means the sample mean is ______ from the population mean.

statistically different

Type 1 error

the error that occurs when the null hypothesis is true but is rejected; p(type 1 error)= α

p value

the probability of Type 1 error; the same as alpha level or significance level

alpha/alpha level

the probability of making a type 1 error; the probability that a result will fall in the rare zone and the null hypothesis will be rejected when the null hypothesis is true; usually set at .05 or 5% -abbreviated α

Beta

the probability of making a type 2 error - abbreviated β

power

the probability of rejecting the null when the null should be rejected

common zone

the section of the sampling distribution of a test statistic in which the observed outocme should fall if the null hypothesis is true; typically, 95% of the sampling distribution

critical value

the value that the test statistic must meet or exceed in order to reject the null hypothesis

alpha levels are also called significance levels

true

statistically significant

when a researcher concludes that the observed sample results are different from the null-hypothesized population value.

the common zone of the sampling distribution of the mean is centered around a z score of ____

zero

hypothesis testing

In statistics, its the procedure in which data from a sample is used to evaluate a hypothesis about a population.

Type 2 error

Null hypothesis should be rejected, but isnt p(type 2 error)= β