Introduction to Statistics

Random Sample severally member of the population has the same chance of creation selected Re layative Sample characteristics should represent those of the target population without bias Observational Study no interposition by the investigator, no treatment imposed Experimental Study Investigator has some control everyplace the determinant Variables Categorical each observation falls into a feline number of groups Nominal named variables with no implied order e. G. Personality type Ordinal grouped variables with implied order e. G. Veil of education Continuous metrical variables Discrete take discrete encourages e. G. Number of children Numerical screw assume any value within a certain range/elemental e. G. Height Types of Designs True experiment researcher has potency to randomly allocate observations to conditions Quasi-experiment demonstrate a relationship between an IV/DVD researcher imprints white plague of naturally occurring groups, pilet make cause and effect state ments Non-experiments (correlation design) question If there Is a relationship between variables, cant make cause & effect statementsBetween groups two groups being compared on some outcome measure Within-subjects participants experience each condition of an IV, with measurements of some outcome taken on each occasion Extraneous variables variable present In an experiment, which might Interfere with the relationship between IV & DVD Confounding variables mediating variable that can adversely affect the relation between IV/DVD Internal validity extent to which a casual relationship can be assumed between IV & DVD.External validity degree to which you can generalize the results of your study to mom underlying population T-test One sample t-test A data should draw close from a normal population Paired t-test -A must be independent, arise from a normal statistical distribution & populations of same spreads Independent sample A normally distributed, homogeneity of variances, independe nce of the observations Correlation/Regression A the relation in the population is linear, the residuals in y have a constant standard remainder and the residuals arise from a normal distribution detests of good fit and test of independence A pass judgment count has to be larger than five