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Psychological Statistic: Midterm
Statistics - numeric facts about Psychology descriptive statistics - brief informational coefficients that summarize a given data set Variable - Characteristic that varies across person and situation Dependent Variable - The outcome factor; the variable that may change in response to manipulations of the independent variable. independent variable - variable that is manipulated Discrete Variable - Any value within given range (with Decimal) Continuous Variable - No intermediate value (whole number) Categorical - characterized by category level of measurement -
nominal, ordinal, interval, ratio level of measurement (NOMINAL) - by category level of measurement (ORDINAL) - By rank level of measurement (INTERVAL) - no absolute zero level of measurement (RATIO) - has an absolute zero Parametric -
- Random Sampling
- Normal Distribution
- either Interval or Ratio
- Homogeneity Non- Parametric - A "distribution-free" test. These tests do not assume a normal sampling distribution probability sampling - random, stratified, systematic, cluster probability sampling (RANDOM) -
- 1/
- almost impossible to do
non-probability sampling (Incidental) - no statistical basis Experimental - to explore cause and effect; manipulate one or more factors; use random assignment Quasi-Experimental - cannot imply cause and effect; and it does not use random assignment Non-Experimental ( Descriptive) - Describing...not predicting...no experiments Non-Experimental (Regression Research) - Test of PREDICTION Non-Experimental (Correlation Research) - Least likely to experience causality Non-Experimental (Comparative research) - Test of DIFFERENCE Frequency Table - A table that uses numbers to record, analyze and interpret data. Array - arranged data to "Highest to Lowest" Simple frequency distribution -
a table that organizes the data based on how often the scores occur Cumulative Frequency - The sums of the frequencies of the data values from smallest to largest. Relative Frequency - -The proportion
- rf = F/N Cumulative Relative Frequency -
- the sum of relative frequency up through, and including, the category of interest
- crf = cf/N or last rf + next rf ... Cumulative Percentage Frequency -
- cpf = crf * 100 Bar Graph -
- Nominal Histogram -
- continuous data Frequency polygon - graph of a frequency distribution that shows the number of instances of obtained scores, usually with the data points connect by straight lines Cumulative frequency polygon -
- comparable to normal distribution Bi-modal - When there are two modes in a set of numbers Tri-modal - Distributions of data having three values occurring with equal frequency. normal distribution -
- A function that represents the distribution of variables as a symmetrical bell-shaped graph.
- Shapiro wilk should be greater than 0. positively skewed distribution -
- A distribution where the scores pile up on the left side and taper off to the right.
- Floor effect negatively skewed distribution -
- A distribution in which most scores pile up at the high end (right side) of the scale.
- ceiling effect Range - the difference between the highest and lowest scores in a distribution Mean deviation - Measure of variation equal to the sum of the deviations of each value from the mean. deviation score - score minus the mean
Variance - the square of the standard deviation standard deviation - a measure of variability that describes an average distance of every score from the mean skewness - a measurement of the distortion of symmetrical distribution or asymmetry in a data set. hypothesis testing - a decision-making process for evaluating claims about a population one- tailed test -
- A hypothesis test in which rejection of the null hypothesis occurs for values of the test statistic in one tail of its sampling distribution.
- area of rejection = + / - 1.
- ( it is not significantly less than / greater than) two-tailed test - A hypothesis test in which rejection of the null hypothesis occurs for values of the test statistic in either tail of its sampling distribution.
- are of rejection = ± 1.
- ( there is a significant difference) Steps in Hypothesis Testing -
- state the null hypothesis
- select statistical test ( one-sample z-test)
- select the sample and collect data
- find the region of rejection
the effect size of T-Test ( one-sample t-test) - d= mean difference / SD the effect size of T-Test ( Two-Independent sample t-test) - the effect size of T-Test ( two-dependent sample t-test) - Interpreting effect size -
