Statistics Glossary: Terms and Definitions, Quizzes of Psychology

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TERM 1 Frequency DEFINITION 1 number of observations that fall in a categorysum of frequency=N TERM 2 Proportion DEFINITION 2 proportion of observations that fall in a categoryshould add up to 1 (sum of p=1.0)p=f/Noften interpreted as percentage of sample that got a particular score TERM 3 Cumulative Frequency DEFINITION 3 number of observations at or below a categoryhighest cf=Nlowest score=lowest cf TERM 4 Cumulative Proportion DEFINITION 4 percent of sample at or below a scoreoften used with standardized testscp=cf/Nhighest cp should equal 1 TERM 5 3 Meausures of Central Tendency DEFINITION 5 meanmedianmodegoal: find best representative of data TERM 6 Mean DEFINITION 6 average*best overall: most stable from sample to sample TERM 7 Median DEFINITION 7 middle1/2 the scores are above, 1/2 the scores are belowbest with extreme scores/outliers TERM 8 Mode DEFINITION 8 most frequenttypical valuefor nominal variables TERM 9 Range DEFINITION 9 highest-lowestbad measure of variation: most affected by outliers TERM 10 Standard Deviation DEFINITION 10 typical distance of a score from the mean TERM 21 Disturbance Variable DEFINITION 21 add noise to treatment groups TERM 22 Population DEFINITION 22 every instancepopulation parameters TERM 23 Sample DEFINITION 23 subset of a populationsample statistic TERM 24 Inferrential Statistic DEFINITION 24 allows us to study samples but make generalizations to populationst statistic, f statistic, chi-square statisticmust refer back to descriptive statistic TERM 25 Descriptive Statistic DEFINITION 25 used to describe sample characteristicsfrequency, central tendency, variability TERM 26 Sampling Error DEFINITION 26 difference between population parameter and corresponding sample statisticsampling error for a mean: standard error of the meansstandard deviation of a distribution of sample means: typical distance a sample mean is from u (mu) TERM 27 Construct DEFINITION 27 underlying idea or factor that causes outcomenot directly observableex. stress, intelligence, motivation TERM 28 Operational Definition DEFINITION 28 defines a constructex. define motivation TERM 29 Scales DEFINITION 29 from least informative to most informative:nominalordinalintervalratio TERM 30 Nominal DEFINITION 30 categoricalex. male, femalenumbers have no numerical meaning, ex. 1=male, 2=female TERM 31 Ordinal DEFINITION 31 higher numbers=more, but don't know by how muchranked/orderedex. best to worst TERM 32 Interval DEFINITION 32 numbersno absolute 0equal intervalsmost likely usedex. IQex. temperature in F: 0 degrees F doens't mean absence of heat TERM 33 Ratio DEFINITION 33 equal intervals with absolute 0physical variablesex. number of stuents, 0 means no studentsheightweight TERM 34 Discrete Measurement DEFINITION 34 each possible observation is an indivisible unitno roundingex. whole numbers: number of kids in a family TERM 35 Continuous Measurement DEFINITION 35 numbers aren' limited to specific categoriesalways end up roundingURL, LRL TERM 46 Independent Groups T-Test DEFINITION 46 2 groupseach person is in one and nly one groupDV is interval or rationo matchingassumptions: normality, independence, homogeneity of varience TERM 47 Related Groups T-Test DEFINITION 47 1. within subjects: each person in both levels of treatment2. matched pairs: *matching variable must relate to outcome3. naturally paired TERM 48 Carry Over Effects DEFINITION 48 being in one treatment effects outcome of second treatment (within subjects design)confounding variabledue to: prediction/learning boredum guessing experimenter's hypothesis TERM 49 Counterbalancing DEFINITION 49 carry over effects from being a confound to a disturbance variableallowing you to interpret events1/2 txt 1-->txt 21/2 txt 2-->txt 1 TERM 50 Single Factor ANOVA DEFINITION 50 test about means3 or more groups/conditionsDV: interval/ratioIV must be between subjects-only 1 level of txt per personHo: all sample means equalH1: not all sample means equalAssumptions:1. normal distribution2. equal homogeneity of variance3. independence TERM 51 Variance Between Groups DEFINITION 51 1. treatment effects2. individual difference3. random error TERM 52 Variance Within Groups DEFINITION 52 sampling error:1. individual differences2. random error TERM 53 Ho True (Single Factor ANOVA) DEFINITION 53 no variation due to txtvariation due to txt=0F ratio=1 TERM 54 Ho False (Single Factor ANOVA) DEFINITION 54 txt effects>0F ob>1 TERM 55 Two Factor ANOVA DEFINITION 55 2 different IVs being studied in a signle experientIVs combined factorially/are "crossed" TERM 56 Main Effects DEFINITION 56 average effects of one IV averaging over the levels of the other IV TERM 57 Interaction DEFINITION 57 when the effect of one IV differs depending on the level of the other IVmoderation: interaction of one IV moderates (changes) effects of other IV TERM 58 Correlation DEFINITION 58 identify size and direction of a relationship between two variablesmeausre linear associationdf=N-2Ho: no correlationH1: there is a correlation TERM 59 Regression DEFINITION 59 derive a predictin equation that ues one variable to predict anotherY=bX+a TERM 60 Chi-Squares Test DEFINITION 60 association between two categorical variabesIV-DV situation both categorizedHo: two variables are unrelatedH1: two variables are relatedAssumptions:1. expected cell frequency >52. independence of observations3. random sampling assumption