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
power is also maximized when a one-tailed test is used (when apropriate) and when the data are analyzed using a _____, ______, or other _______ statistical test
t-test, ANOVA; parametric
The inferential statistical tests are categorized as parametric and nonparametric. Both types of tests share the assumptions that the sample has been ______ from the population and that observations are _______
randomly selected; independent
A ______ test is used when the data being analyzed represent a(n) _____ or ratio scale of measurement and when two assumptions have been met. The first assumption is that, in the population from which the sample was drawn, scores on the variable are _____ distributed. The second assumptions is that there is “homoscedasticity,” which means that the ______ of the populations that the different groups represent are equal
parametric; interval; normally; variances
if the data to be analyzed do not meet the assumptions for a parametric test or if they represent a(n) ________ or ordinal scale of measurement, a ______ test is used
nominal; nonparametric
the major limitation of the nonparametric tests is that they are less _____ than parametric tests, which means that, when using these tests, it is more difficult to detect a false _____ hypothesis
powerful; null
parametric and nonparametric tests both yield a tests statistic that the researcher compares to a critical value, which is the cutoff point that divides the _____ into the regions of likely and unlikely values.
sampling distribution
The critical value for a particular research study is determined by two factors: _______ and _________
alpha, the degrees of freedom
The chi-square test is used to analyze data collected on a nominal variable (or other variable that is being treated as a nominal variable). The ________ sample chi-square test is used when a study includes only one ______ and data on that variable are reported in terms of _______
single-; variabel; frequencies
It would be an appropriate statistical test when a researcher asks a sample of 40 students to indicate which of 5 textbooks they prefer for an introductory clinical psychology class. The degrees of freedom for this study are equal to _______
(5-1) = 4
The _____ sample chi-square test is used when a study includes _____ or more variables and the data to be analyzed are frequencies in each nominal category
multiple; 2
It would be the appropriate statistical test when a hospital director wants to compare the number of current adult male, adult female, adolescent male, and adolescent female in-patients who have received a primary diagnosis of either MDD, bipolar 1, bipolar 2, or Mood disorder NOS. The degrees of freedom for this study are equal to ______
(4-1)(4-1) =9
The Mann-Whitney U test and the Wilcoxon matched-pairs test are used to analyze data when a study includes one ______ variable with two levels and the data to be analyzed are reported in terms of ______
independent; ranks
The Mann-Whitney U test is appropriate when the two groups are ______, while the Wilcoxon test is used when the groups are _______
independent (unrelated); correlated (related)
although they can be used to analyze data from studies involving more than two means, this is problematic because it increases the ________ error rate which refers to the chance of making a _____ error
means; experimentwise; Type I
the t-test for a single sample is appropriate for comparing an obtained ______ to a known ______
group (sample) mean; population mean
the degrees of freedom for a t-test for a single sample are equal to _____ where N= the number of subjects in the sample
(N-1)
the t-test for _______ samples is used to compare two means when groups are related
correlated
related groups are obtained in several ways. One way is by matching subjects in pairs on the basis of their status on a(n) _______ variable. Another way is for subjects to act as their own _____ (comparison) group
extraneous; control
the degrees of freedom for a t-test for correlated samples equal _______, where N is the number of ______
(N-1); pairs of scores
if a psychologist conducts a study to compare the effects of two weight reduction programs and he matches subjects in pairs in terms of their initial weight and assigns members of each pair to a different program, the t-test for _____ is the appropriate statistical test. If the sample consists of 26 subjects, the degrees of freedom for this study are ______
correlational samples;
(13-1) = 12
The two main forms of analysis of variance are the one-way ANOVA and the factorial ANOVA. The _______ ANOVA is used when a study include one _____ variable and two or more ______ groups.
one-way; independent; independent
the one-way ANOVA yields a single F-ratio, which is calculated by dividing MSB by MSW. MSB is a measure of variability that reflects ________, and MSW is a measure of variability that reflects ________ only
treatment effects and error; error
When MSB is _______ than MSW, the F-ratio is greater than _____, suggesting that the IV has had an effect on the DV
larger; 1.0
the factorial ANOVA is the appropriate statistical test when a research study includes ______ independent variables
two or more
the factorial ANOVA provides a separate F-ratio for the ______ effects of each IV and for the _____ between IVs
main; interactions
if a psychologist conducts a study to compare the effects of four different weight loss programs for males and females, the study’s IVs are _______. Assuming the DV is measured on a(n) _____ or ratio scale, the appropriate statistical test would be the ______ ANOVA
weight loss program and gender; interval; Factorial (two-way)
several forms of the ANOVA are available for more complex research designs. The _____ ANOVA is used when a researcher wants to control an extraneous variable by statistically analyzing its’ effects on the DV
randomized block
the effects of an extraneous variable can be statistically removed by using the ________
ANCOVA
the repeated measures ANOVA is used to analyze interval or ratio data when a ______ subjects research design has been employed
within-
if a study includes at least one within-subjects IV and one between-groups IV, the _______ ANOVA is appropriate
mixed (split-plot)
trend analysis is used for identifying linear and nonlinear trends when the _____ is quantitative
IV
if a study includes one IV and frou DVs, a researcher has a choice between conducting four _____ ANOVAs or a single _______. In this situation, the latter test is usually preferred because it helps reduce the ______
one-way; MANOVA; experimentwise error rate (probability of making a Type I error)
Cohen’s d and eta squared are measures of _______
effect size
According to the Central Limit Theorem, the shape of the sampling distribution of means:
approaches normal as the size of the samples increases regardless of the shape of the population distribution of scores.
(The Central Limit Theorem predicts that the sampling distribution increasingly approaches normal as the sample size (not the number of samples) increases.)
A researcher will use trend analysis to analyze the data she has collected in a research study when:
the independent variable is quantitative
A researcher would use a multivariate analysis of variance (MANOVA) to analyze the data she collects in a study when:
the study includes one or more independent variables and two or more dependent variables
Dr. Terry Tas obtains SAT scores from a sample of 30 high school seniors following their participation in a workshop designed to improve SAT scores. The appropriate statistical test for comparing the mean score obtained by these students to the national mean is which of the following?
t-test for a single sample
(The different forms of the t-test are all used to compare two means, and the t-test for a single sample is used when a sample mean will be compared to a known population mean.)
Increasing the level of significance (alpha) from .01 to .05 will:
increase the probability of making a Type I error but decrease the probability of making a Type II error.
Ninety adults are randomly assigned to one of three groups and the average IQ score of each group is calculated. If a one-way ANOVA is used to compare the mean IQ scores of the three groups, you would expect the resulting F-ratio to be:
equal to 1.0
(When there are no treatment effects (which would be the case in the situation described in this question), the numerator and denominator should both be measures of error and the F-ratio will simply be error divided by error, which should equal a value very close to 1.0)
The chi-square test would NOT be the appropriate test for analyzing data collected from which of the following studies?
a study conducted to compare the number of males and females who say they prefer paper, plastic, or hemp bags for their groceries before and after they view a film on recycling
(One of the assumptions for the chi-square test is independence of observations. In the study described in this answer, the preferences of each participant will be determined twice (before and after viewing the film) and, consequently, the assumption of independence is violated.)
The standard error of the mean (SEM) decreases as:
the population standard deviation decreases and the sample size increases.
(The standard error of the mean is equal to the population standard deviation divided by the square root of the sample size. Plugging numbers into this formula proves that the standard error decreases in size as the population standard deviation (numerator) decreases and or or the sample size (denominator) increases. See the Statistics and Research Design chapter of the written study materials for examples of the effects of changing the standard deviation and sample size on the size of the standard error of the mean.)
The t-test for dependent samples is used to analyze the data collected in a study involving 36 participants who had been matched on an extraneous variable before being assigned to one of the two treatment groups. The degrees of freedom for this study are:
17
In this study, there are 18 pairs of scores, so the degrees of freedom are (18 - 1), or 17.
When a researcher compares the difference between two means to assess the effects of an independent variable on a dependent variable, she will have the most confidence in her decision to reject the null hypothesis if her results are statistically significant at the ___ level of significance.
0.01
When assessing the impact of gender on preference for three different study methods (written materials, workshop, combination of written materials and workshop), you would use which of the following statistical tests to analyze the data you collect from 100 psychologists who have just started preparing for the licensing exam?
multiple-sample chi-square test
The chi-square test is the appropriate test when the data to be analyzed represent a nominal scale; and, when the study includes more than one variable, the multiple-sample chi-square test is the appropriate test. (A useful way to distinguish between the single-sample and multiple-sample chi-square tests is to substitute the word “variable” for “sample” in their names – and keep in mind that, when you count the variables, you count the independent and dependent variables.)
What would increase the power of a statistical test?
increasing the sample size
