Nasih Jaber Ali

Scientific and disciplined inquiry is an orderly process, involving: problem Recognition and identification of a topic to be studied (“problem”) method Description and execution of procedures to collection information (“method”) analysis Objective data analysis results Statement of findings (“results”)

Quantitative Quantitative… data instruments Collects and analyzes numerical data obtained from formal instruments

 Descriptive research (“survey research”)  Correlational research  Causal-comparative research (“ex post facto research”)  Experimental research

dependent variable independent variable At least two different groups are compared on a dependent variable or measure of performance (called the “effect”) because the independent variable (called the “cause”) has already occurred or cannot be manipulated

Independent… An activity of characteristic believed to make a difference with respect to some behavior experimental variable, cause, treatment

The change or difference occurring as a result of the independent variable criterion variable, effect, outcome, posttest

A study in which the researcher attempts to determine the cause, or reason, for pre-existing differences in groups of individuals…. called an “ex post facto” study because both the effect and the alleged cause have already occurred and must be studied in retrospect

 Causal-comparative studies… * attempt to identify cause-effect relationships  Correlational studies… * attempt to identify relationships

 Causal-comparative studies … * involve two (or more) groups and one independent variable  Correlational studies… * typically involve two (or more) variables and one group

 Causal-comparative studies … * involve making comparisons  Correlational studies … * involve establishing relationships

 Causal-comparative studies… * individuals are not randomly selected but selected because they belong to groups  Experimental studies… * individuals are randomly selected and assigned to two (or more) groups

 Causal-comparative studies … * the researcher cannot manipulate the independent variable  Experimental studies … * the researcher manipulates the independent variable

 Causal-comparative studies… * the independent variable has already occurred and cannot be manipulated  Experimental studies… * the researcher manipulates the independent variable to determine its effects

1. Select the problem 2. Select participants and instrument 3. Design and procedure 4. Data analysis and interpretation

* The researcher starts with an effect and seeks its causes * The independent variable cannot or should not be manipulated

* Select samples representative of their respective populations and similar with respect to critical variables other than the independent variable comparison groups * called “comparison groups”

instrument * The performance of the groups is compared using some valid dependent variable measure (“instrument”) * Lack of randomization, manipulation, and control are sources of weakness

* The process by which the researcher attempts to ensure that the findings are as free of researcher bias and error as possible

* Random assignment of participants to groups * Pair-wise matching * Comparing homogeneous groups * Comparing homogeneous subgroups * Factorial analysis of variance * Analysis of covariance

* Not possible in causal-comparative studies because the groups already exist and have already received the treatment

* First: find a participant in the second (third, fourth, etc.) group with the same or similar score on the control (non manipulated) variable as the participant in the first group * Second: if a participant in either group does not have a suitable match, the participant is eliminated from the study

* Control for extraneous variables that are homogeneous with respect to the extraneous variables * Limitation: lowers the number of participants in the study and, of course, limits the generalizability of the findings

* Form subgroups within each group that represent all levels of the control (non manipulated) variable * Controls for the variable and also permits the researcher to determine whether the independent variable affects the dependent variable differently at different levels of the control (non manipulated) variable

* Building the control (non manipulated) variable into the research design factorial analysis of variance * Then use factorial analysis of variance to analyze the results to determine the effect of the independent and control (non manipulated) variable on the dependent variable, both separately and in combination

Factorial analysis of variance  Factorial analysis of variance Allows the researcher to determine if there is an interaction between the independent variable and the dependent variable such that the independent variable operates differently at different levels of the independent variable building it into the research design

* Statistically adjusts initial group differences on a dependent variable for initial differences on some other variable related to performance on the dependent variable * Removes initial differences so that the results can be fairly compared as if the two groups started equally

* Researcher uses a variety of descriptive and inferential statistics :Mean Standarddeviation Standard deviationt-test Analysis of variance

* The descriptive statistic indicating the average performance of an individual or group on a measure of some variable

* The descriptive statistic indicating the spread of a set of scores around the mean

* The inferential statistic indicating whether the means of two groups are significantly different from one another

* The inferential statistic indicating the presence of a significant difference among the means of three or more groups

 Jack R. Franenkel, Norman E. Wallen. How to design and evaluate research in education  Louis Cohen, Lawrence Manion. Research methods in education