PSYC 381: Exam 3 UPDATED ACTUAL
Questions and CORRECT Answers
Sampling Error - CORRECT ANSWER natural discrepancy, or amount of error, between a sample statistic and its
corresponding population parameter
Distribution of Sample Means - CORRECT ANSWER collection of sample means for ALL possible random
samples of a particular size (n) that can be obtained from a population
Central Limit Theorem - CORRECT ANSWER distribution of sample means will approach a normal distribution
as n approaches infinity; n must be greater than or equal to 30 and population from which samples is normal
Expected Value of M - CORRECT ANSWER sample mean will equal population mean if we can plot every
possible sample mean from the population
Law of Large Numbers - CORRECT ANSWER states that the larger the sample size (n), the more probable it is
that the sample mean is close to the population mean
Standard Error - CORRECT ANSWER distance that the sample mean value deviates from population mean
Hypothesis Testing - CORRECT ANSWER statistical method that uses sample data to evaluate a hypothesis about
a population
Inferential Statistics - CORRECT ANSWER procedures for determining whether sample data represent a particular
relationship in the population
Null Hypothesis - CORRECT ANSWER states in the general population that there is no change, no difference, no
association, or no relationship; Ho predicts that the independent variable (treatment) will have no effect on the dependent
variable for the population; there is no association between the groups and group means are equal
Alternative Hypothesis - CORRECT ANSWER states that there is a change, a difference, or a relationship for the
general population; alternative hypothesis predicts that the independent variable (treatment) will have an effect on the
dependent variable, symbol is H1; there is an association between the groups and group means are not equal
Critical Region (C.R.) - CORRECT ANSWER composed of extreme sample values that are very unlikely to be
obtained if Ho is true; boundaries are determined by alpha level
If sample data falls in critical region - CORRECT ANSWER we reject Ho
Type I Error - CORRECT ANSWER occurs when we reject a true null hypothesis (Ho) the alpha level determines
the probability of committing a type I error; false positive
Type II Error - CORRECT ANSWER occurs when we fail to reject a false null hypothesis (Ho) and Beta (B) is
probability of committing a type II error; false negative
Power - CORRECT ANSWER finding a significant treatment when in fact it exists ( 1 - Beta ); setting significant
level low or reducing number of subjects will reduce power; increased power reduces type II errors; increasing sample
size leads to more power
Parametric Assumptions - CORRECT ANSWER inferential procedures that require certain assumptions about the
raw score population represented by the sample, used when we compute mean of the score
Parametric Assumptions (Specific) - CORRECT ANSWER all observations are randomly and independently
samples from their parent pop; the pop distributions from which samples are selected are normal; all populations have
same variance (homogeneity of variance); data are measured on at least an interval scale
Parametric Assumptions More Powerful than Nonparametric Tests If - CORRECT ANSWER all of the
assumptions underlying the parametric test hold, the nonparametric test is based on a scale of measurement < interval
Questions and CORRECT Answers
Sampling Error - CORRECT ANSWER natural discrepancy, or amount of error, between a sample statistic and its
corresponding population parameter
Distribution of Sample Means - CORRECT ANSWER collection of sample means for ALL possible random
samples of a particular size (n) that can be obtained from a population
Central Limit Theorem - CORRECT ANSWER distribution of sample means will approach a normal distribution
as n approaches infinity; n must be greater than or equal to 30 and population from which samples is normal
Expected Value of M - CORRECT ANSWER sample mean will equal population mean if we can plot every
possible sample mean from the population
Law of Large Numbers - CORRECT ANSWER states that the larger the sample size (n), the more probable it is
that the sample mean is close to the population mean
Standard Error - CORRECT ANSWER distance that the sample mean value deviates from population mean
Hypothesis Testing - CORRECT ANSWER statistical method that uses sample data to evaluate a hypothesis about
a population
Inferential Statistics - CORRECT ANSWER procedures for determining whether sample data represent a particular
relationship in the population
Null Hypothesis - CORRECT ANSWER states in the general population that there is no change, no difference, no
association, or no relationship; Ho predicts that the independent variable (treatment) will have no effect on the dependent
variable for the population; there is no association between the groups and group means are equal
Alternative Hypothesis - CORRECT ANSWER states that there is a change, a difference, or a relationship for the
general population; alternative hypothesis predicts that the independent variable (treatment) will have an effect on the
dependent variable, symbol is H1; there is an association between the groups and group means are not equal
Critical Region (C.R.) - CORRECT ANSWER composed of extreme sample values that are very unlikely to be
obtained if Ho is true; boundaries are determined by alpha level
If sample data falls in critical region - CORRECT ANSWER we reject Ho
Type I Error - CORRECT ANSWER occurs when we reject a true null hypothesis (Ho) the alpha level determines
the probability of committing a type I error; false positive
Type II Error - CORRECT ANSWER occurs when we fail to reject a false null hypothesis (Ho) and Beta (B) is
probability of committing a type II error; false negative
Power - CORRECT ANSWER finding a significant treatment when in fact it exists ( 1 - Beta ); setting significant
level low or reducing number of subjects will reduce power; increased power reduces type II errors; increasing sample
size leads to more power
Parametric Assumptions - CORRECT ANSWER inferential procedures that require certain assumptions about the
raw score population represented by the sample, used when we compute mean of the score
Parametric Assumptions (Specific) - CORRECT ANSWER all observations are randomly and independently
samples from their parent pop; the pop distributions from which samples are selected are normal; all populations have
same variance (homogeneity of variance); data are measured on at least an interval scale
Parametric Assumptions More Powerful than Nonparametric Tests If - CORRECT ANSWER all of the
assumptions underlying the parametric test hold, the nonparametric test is based on a scale of measurement < interval
