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Flashcards in Stats Deck (83)
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Main and interaction effects

Main effect- effect of one IV on the DV, disregarding the effects of all other independent variables.
Interaction- refers to the effects of two or more IV's considered together and occurs when the effects on an IV differ at different levels of another IV.


Single Subject Designs

includes at least one baselines ( no treatment) phase and one treatment phase
the DV is measured repeatedly at regular intervals throughout the baseline and tx phases, repeated measure helps control any maturational effects that migh otherwise threaten the studys internal validity


AB Design

includes a single baseline( A) and a single treatment ( B) , dependent variable is measured at regular intervals during both phases


Reversal ABA, ABABA designs

more than one baseline and treatment, provide additonal control over potential threats to a studys internal validity. when an ABAB design is used, is status on the DV returns to the intitial baseline during the second A phase, and then to its previous treatment level during the second B phase , an investigator can be certain that any observed change in the DV is due to the IV
*considered inappropriate when withdrawl of a treatment during the course would be unethical


Multiple Baseline

does not require withdrawing a treatment during the course of the study, but applying sequential different behaviors of the same subject, to the same subject ind different settings to the same subject on different tasks


Nominal Scale

divides variables into unordered categories, do not provide information on the order of the catergories, religion, political affiliation, place of birth


Ordinal Scale

divides observations into categories but also provides information on the order of those categories
Ratings and ranks on a likert scale are examples or ordinal scale scores


Interval Scale

property of order as well as property of equal intervals between sucessive points on the scale, scores on standardized IQ tests considered to represent an interval scale


Ratio Scale

properties or order and equal intervals as well as an absolute zero point which measn that a score of 0 indicates a complete absence of the characteristic being measured


Normal Curve

symmertrical, bell shaped, and defined by specific mathamtical formula,


Areas under the normal curve

Leptokurtic- more peaked than the normal distribution,
Platykurtic- when distribution is flatter
Mesokurtic- normal curve


Positively vs Negatively Skewed Distribution

Positvely Skewed- most of the scores are in the negative low score side of the distribution and the positive tail is extended because of the presence of few high scores
Negatively Skewed distribution- most scores are located in the positive high end side of the distrbution and the negative tail is extended due to the presence of few low scores



score or catergory that occurs the most frequently in a set of data



score that divides a distribution in half when the data that has been ordered from low to high, when a distrubution has a odd number of observations, the median is equal to the middle of observations



is the average



calculated by subtracting the lowest score from the highest score


Standard Deviation

calculated by taking the square root of the variance which converts it to the same unit of measurement as the orginal score,


Sampling Distribution of the Mean

is the distrubution of sample means that would be obtained if an infinite number of equal size samples were randomly selected from the population and the mean for each sample was calculated


Retention and Rejection regions

Retention- region of likely values lies in the central portion of the sampling distribution and consists of the values that are likely to occur as a consequence of sampling error only
Rejection- region of unlikely values lies in one or both tails of the sampling distributions and consists of the values that are likely to occur as a consequence of sampling error only


Areas under the normal curve-

when a disturbition is normal 68.26% of the scores fall between plus or minus 1 of the standard deviation, 95.44% fall between plus 2 and minus 2, and 99.72 fall between plus 3 and minus 3.


Null Hypothesis

stated in a way that implies that the independent variable does not have an effect on the dependent variable


Alternative Hypothesis

states the opposite of the null hypothesis and implies that the independent variable does have an effect


Parametric Tests

include the t test are used to evaulate hypotheses about population means, variances or other parameter, tests are appropriate only when the variable of interest has been measured on an interval or ratio scale and when certain assumptions about the population distrubution are met.


Nonparametic Tests

are used to analyze data collected on variables that have been measured on an nominal or ordinal scale , used to evaulate hypotheses in the shape of a distrubution rather than the distrubutions mean variance or other paramter, such as the chi square test, Mann Whitney U test,


Single sample Chi Square test

also known as the goodness of fit test-


Multiple Sample Chi Square Test

is used when a descriptive or experimental study that includes two or more variables and the data can be analyzed are the frequency of observations in each category


t test for single sample

used when a study includes only one group and the group(sample) will be compared to a known population mean


t test for independent samples

appropriate statical test when a study includes two independent groups and the means of the two groups will be compared


t test for correlated samples

used when the two means to be compared have come from correlated groups , it is the appropriate test for a study using a within subjects design in which a single group of subjects wil be compared to itself before and after the IV has been applied.


One way ANOVA

used when a study includes one IV and two or more independent groups and one DV that is measured on an interval or ratio scale. divdies the total sum of swuares into a between groups and a within group sum of squares