Inferential Statistics

used when a researcher wants to infer, or conclude/suggest from evidence and reasoning, something about a larger population based on a sample used in a study

inferential statisitics are often divided into two categories

assume that the distribution of scores in the sample are normally distributed
- utilize means and standard deviations

statisitics are distribution free
- can compare categorical and rank order data
- appropriate when comparing differences in percentages for groups

is a number that expresses the probability that the result of a given experiment or study could have occurred purely by chance.

is the amount of risk you are willing to assume when conducting a study.

what is the level of significance used by most researchers

Statistical significance is reported as a _________, an abbreviation for _________.

how likely something is to happen a

the most basic of inferential difference statistics because it examines the difference between two groups at a single point in time, or one group at two time points.

(also known as a two-group/two-sample t-test or an unpaired sample t-test) compares the difference in the mean score for two unrelated groups (between-group comparison).

(also referred to as a paired-sample t-test) compares the pretest and posttest scores of a single group (within group comparison).

the test for comparing more than two means.

(similar to the between-group t-test) compares three or more groups on a single dependent measure.

(similar the within-group t-test) is used when the means are compared over three or more time points.

is used when between- and within-group analyses are conducted simultaneously (two or more groups are compared over two or more time points).

used when a researcher wants to statistically control a variable that could affect the outcome of a study.

Useful when a demographic variable differs between groups and when that demographic variable is related to the outcome variable (dependent variable)

used when the assumptions for parametric statistics are not met: the data is not normally distributed (this requires a sample size of 30 or more participants)

determines if there is a statistically significant difference between frequencies in two or more groups.

compares two groups and is used when the parametric assumptions are not met (comparable to the independent sample t-test).

similar to the Mann-Whitney test, but it is used when three or more groups are compared (nonparametric equivalent of the one-way ANOVA).

describes the magnitude or strength of a statistic.

measures the difference between two group means reported in standard deviation units
- More commonly used with t-test

____ squared (n2) and _____ squared (w2) are other common ES statisitcs.

Whenever a statistic is calculated, the result reflects the statistic of the sample, but it is an ___________ estimate of the population.

is a reliability estimate that suggests the range of outcomes expected for the population.

provides a range of numbers in which the true score of the population likely falls

CI small range =
CI large range =

provides information about the likelihood of detecting a difference if it exists.