ED 502: EDUCATIONAL STATISTICS TESTS OF RELATIONSHIP STATISTICAL TREATMENT Pearson - r Spearman RankOrder Correlation / Spearman Rho FUNCTION USE LEVEL/SCALE OF MEASUREMENT It is used to determine if there is a correlation or relationship between two variables of the interval or ratio type. Interval / Ratio It is used to determine if there is a correlation or relationship between two variables of the ordinal type. Ordinal * product-moment correlation Independence It is used to determine if there is a correlation or relationship between two variables of the nominal type. Scores, Grades, Ratings Ex. Reading Comprehension Personality * nonparametric statistics (distribution free statistics) Chi-Square Test of SAMPLE DATA Nominal SAMPLE PROBLEM Is there a positive correlation between Reading Comprehension and Personality of PNU graduate students? Is there a significant relationship between the Student Academic Achievement in Math II and Instructional Level among PNU undergraduate students? Ranks, Non-numeric scales Is there a correlation between Motivation and Self-Concept? Ex. Satisfaction Happiness Motivation Self-concept Discomfort What type of affective need is addressed by the type of management of emotions? Categorical / Classificatory Variables 50 Male high school students and 50 Female high school students were asked about their color preferences. Among the Male students, 20 preferred light colors, 15 preferred bright and 15 preferred dark. Of the 50 Female students, 15 preferred light colors, 15 preferred bright and 20 preferred dark colors. Ex. Sex Drink Preference Color Preference Is sex related to color preferences? TESTS OF DIFFERENCE STATISTICAL TREATMENT One Population Z - Test FUNCTION USE LEVEL/SCALE OF MEASUREMENT SAMPLE DATA It is used to determine if the given sample mean was drawn from the population with no parameters or if a given group represent the population. Interval / Ratio 2 groups – single interval variable Ex. Group of Teachers (sample mean) from the University (population) Group of Teenagers (sample mean) from the Metro Manila (population) * random / purposive sampling Z - Test of Independent Proportions It is used to determine if there is a significant difference between two independent / different groups or situations that call for two types of responses (dichotomous). * include issues in which you are only asked whether you agree or disagree Nominal Frequencies converted to Proportions (2 groups – 2 responses) Ex. Yes and No Agree and Disagree In Favor and Against SAMPLE PROBLEM The given population obtained a mean of 120 and the standard deviation is 20. A sample of 100 was drawn from the population and it obtained a mean of 119. Test the hypothesis that the sample mean of 119 was drawn from the population whose mean is 120. 50 Male graduate students and 50 Female graduate students were asked whether they are in favor or against same sex marriage. Among Male respondents, 25 are in favor and 25 are against. Among Female respondents, 20 are in favor and 30 are against. Is there a significant difference between Male and Female graduates who are in favor of same sex marriage? 90 Ph.D candidates in Educ. Mgt. and 80 Ph.D candidates in Math respond to an item concerning the usefulness of Foreign Language requirement for the Ph.D. 30 Educational Mgt. candidates and 55 Math candidates agree with the statement. Is there a significant difference between the proportions in each group that responded In Favor? Z - Test of Dependent Proportions It is used to determine if there is a significant difference between pair of observations from a single group. Nominal Pair of Observations Ex. Before and After In Favor and Against Passed and Failed * response to a question given in two different occasions Is there a significant difference in the responses of the 50 voters before and after the Meeting de Avance? Consider the test items A and B. In a sample of 100 children, 30 pass item A fail item B, whereas 20 fail item and pass item B. Are the proportions of children passing the two items significantly different from each other? T - Test of Independent / Uncorrelated Means It is used to determine if there is a difference between two groups using dependent independent variables. Interval / Ratio 2 groups – Control and Experimental Group Ex. Method of Teaching Achievement IQ Scores * comparison of two groups Is there a significant difference between the experimental and control group in terms of achievement in Statistics? A survey was conducted on attitude toward mentally impaired children. A random sample of teachers and administrators were selected and asked to respond to an attitude toward mentally impaired children scale. Is there a significant difference between teachers and school administrators in terms of attitude toward mentally impaired children? T - Test of Dependent / Correlated Means It is used to determine if there is a significant difference between two sets or two groups of correlated scores or measures. Interval / Ratio 2 groups – Pre-test and Post-test Ex. Scores Is there a significant difference between the Pre-test and Post-test in Statistics of the Experimental Group? Is there a difference in the Pre-test and Post-test scores in the Math Achievement test of Grade IV pupils when exposed to traditional method? calculator-integrated method? Chi-Square Test of Goodness of Fit One-Way Analysis of Variance (ANOVA I) It is used to determine if there is difference between the observed (hypothetical / theoretical) distribution and expected (predetermined) distribution. It is used to determine if there is a significant difference between two or more groups in terms of means (achievement, weight, IQ). Nominal Ex. Responses Strongly Agree (SA) Agree (A) No Opinion (NO) Strongly Disagree (SD) Disagree (D) Interval / Ratio of Variance (ANOVA II) It is used to determine if there is an interaction / combined effect between or among two or more independent variables (ex. method of teaching, medium of instruction) to the dependent variable (ex. achievement test). * can answer 3 questions 2 or more groups Ex. Method of Teaching: I – Discovery Approach II – Distance-Learning III – Instructional-TV * extension of T-test / inspects an independent variable Two-Way Analysis Frequencies, Scale, Opinion, Response Interval / Ratio 2 or more groups Ex. Effect of Method of Teaching and Medium of Instruction to Achievement 100 students were asked about their opinion about Pacquiao’s candidacy. 23 strongly agreed, 21 agreed, 5 expressed no opinion, 25 disagreed and 26 strongly disagreed. Is there a significant difference between the observed distribution and expected distribution of the students’ responses on the said issue? Are the observed frequencies the same as an expected set of frequencies? (Ex. Are the number of workplace accidents the same for each hour of the day?) Do the three groups of graduate students (discovery approach, distance learning, instructional TV) differ significantly in terms of achievement in Statistics? A researcher was interested in whether an individual's interest in politics was influenced by their level of education and gender. Therefore, the dependent variable was "interest in politics", and the two independent variables were "gender" and "level of education". Is there an interaction between education level and gender / was the effect of level of education on interest in politics different for males and females? LEVELS OF MEASUREMENT NOMINAL ORDINAL INTERVAL STATISTICAL Chi-Square Test of Independence Spearman Rank-Order Pearson - r TREATMENTS Z - Test of Independent Proportions Correlation / Spearman Rho One Population Z - Test TO BE USED RATIO Z - Test of Dependent Proportions T - Test of Independent / Uncorrelated Means Chi-Square Test of Goodness of Fit T - Test of Dependent / Correlated Means One-Way Analysis of Variance (ANOVA I) Two-Way Analysis of Variance (ANOVA II) STATISTICS / proportions percentage MEASURES Median Quartile Deviation PRE-TEST POST-TEST CONTROL GROUP DESIGN: EXPERIMENTAL GROUP Pre-test Post-test CONTROL GROUP Pre-test T - Test of Independent Means Means LEVEL OF SIGNIFICANCE ∝ .05 you have 5 chances (Type I Error) out of 100 that you are wrong with your decision and 95% that you’re correct; rejecting the null hypothesis when it should be accepted; has smaller Region of Acceptance and bigger Region for Rejection ( any computed Z-value or absolute value 1.96, reject Ho ) ∝ .01 you have 1 chance (Type II Error) of being wrong and 99% that you’re correct; accepting the null hypothesis when it should be rejected; has bigger Region of Acceptance and smaller Region for Rejection ( any computed Z-value or absolute value 2.58, reject Ho) DECISION – INTERPRETATION OF HYPOTHESIS Significant REJECT use Alternate Hypothesis Not Significant GUIDE IN CHOOSING STATISTICAL TREATMENT: 1) Determine the type of research question to be answered by the statistical analysis. a. the degree of relationship or dependence among variables (H0 = there is no relationship or dependence, and the statistical test answers the question as to whether any relationship or dependence found is sufficiently different from zero that it can be considered “statistically significant”.) b. the significance of group differences (H0 = there is no difference between groups. The statistical test answers the question as to whether an observed difference is probably due just to random factors, or is large enough to be considered “statistically significant” and due to the treatment factor.) T - Test of Dependent T - Test of Dependent Means Post-test Mean Standard Deviation ACCEPT use Null Hypothesis 2) Determine the nature(s) of the variables under discussion, and whether they meet the assumptions of a particular test (e.g. the data are normally distributed). 3) Types/levels of data: NOMINAL – unordered categories; numbers simply express identity/ labeling purposes (e.g. religion; country of birth; sex; etc.) ORDINAL – ordered categories; numbers express ranks (e.g. level of agreement on an opinion survey; proficiency level at a martial art; scale used in determining the hardness of a mineral, academic ranks) for nominal and ordinal data, what is usually recorded is the number of occurrences of a particular result (e.g. number of Christians, number of Buddhists etc. but these numbers are not the values of the variable. In this case, variable = religion, values = Christian, Buddhist, …and the numbers are the number of occurrences of a particular value.) INTERVAL – ordinal + distance between values is of constant size; has equal intervals that is distances between points are equal starting an arbitrary zero (e.g. temperature; score) RATIO – interval + (i) there is a meaningful zero and (ii) the ratio between two numbers is meaningful; zero is absolute; there is absolute value of the variable (e.g. height; weight, distance, number of children) ratio and interval data can be either discrete (i.e. there are gaps between values, e.g. number of children) or continuous (i.e. there are no gaps between values (e.g. weight, height).