Which type of research design is used when data is collected at two or more points in time?

What are the main types of qualitative approaches to research?

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PPA 696 RESEARCH METHODS
PRE-EXPERIMENTAL DESIGNS
What type of research design collects data at two or more points in time from different samples?
What type of study design investigates two or more variables?
What type of research design is data collection?
What are the 4 types of research design?

While there are many different investigations that can be done, a study with a qualitative approach generally can be described with the characteristics of one of the following three types:

Historical research describes past events, problems, issues and facts. Data are gathered from written or oral descriptions of past events, artifacts, etc. It describes “what was” in an attempt to recreate the past. It is different from a report in that it involves interpretation of events and its influence on the present. It answers the question: “What was the situation?”

Examples of Historical Research:

A study of the factors leading to the historical development and growth of cooperative learning
A study of the effects of the historical decisions of the United States Supreme Court on American prisons
A study of the evolution of print journalism in the United States through a study of collections of newspapers
A study of the historical trends in public laws by looking recorded at a local courthouse

Ethnographic research develops in-depth analytical descriptions of current systems, processes, and phenomena and/or understandings of the shared beliefs and practices of a particular group or culture. This type of design collects extensive narrative data (non-numerical data) based on many variables over an extended period of time in a natural setting within a specific context. The background, development, current conditions, and environmental interaction of one or more individuals, groups, communities, businesses or institutions is observed, recorded, and analyzed for patterns in relation to internal and external influences. It is a complete description of present phenomena.

One specific form of ethnographic research is called a case study. It is a detailed examination of a single group, individual, situation, or site.

A meta-analysis is another specific form. It is a statistical method which accumulates experimental and correlational results across independent studies. It is an analysis of analyses.

Examples of Ethnographic Research:

A case study of parental involvement at a specific magnet school
A multi-case study of children of drug addicts who excel despite early childhoods in poor environments
The study of the nature of problems teachers encounter when they begin to use a constructivist approach to instruction after having taught using a very traditional approach for ten years
A psychological case study with extensive notes based on observations of and interviews with immigrant workers
A study of primate behavior in the wild measuring the amount of time an animal engaged in a specific behavior

Narrative research focuses on studying a single person and gathering data through the collection of stories that are used to construct a narrative about the individual’s experience and the meanings he/she attributes to them.

Examples of Narrative Research:

A study of the experiences of an autistic student who has moved from a self-contained program to an inclusion setting
A study of the experiences of a high school track star who has been moved on to a championship-winning university track team

PPA 696 RESEARCH METHODS

Pre-experimental Design
Cross-Sectional Design
Longitudinal Designs
Time Series Design
Panel Design
Case Study Design
Control over Sources of Invalidity
How to Improve Designs for Description

PRE-EXPERIMENTAL DESIGNS

In general, a research design is like a blueprint for the research. A research design is a plan that guides the decision as to:
-when and how often to collect data
-what data to gather and from whom
-how to analyze the data

More specifically, a research design refers to the type of study that will be conducted, whether it will be pre-experimental, quasi-experimental, or true experimental.

Pre-experimental designs include: -case study design -one group pre-test/post-test design -static group comparison design (cross-sectional study) Quasi-experimental designs include: -time series design (may include panel design) -equivalent time samples design -equivalent materials design -nonequivalent control group (comparison group) design -counterbalanced design -separate sample pre-test/post-test design -separate sample pre-test/post-test control group design -multiple time-series design -recurrent institutional cycle design -regression/discontinuity analysis True experimental designs include: -pre-test/post-test control group design -Solomon four-group design -post-test only control group design Research Methodology concerns how the design is implemented, how the research is carried out. The methodology employed often determines the quality of the data set produced. Methodology is concerned with: -when and how often to collect data -construction of data collection measures -identification of the sample or test population -choice of strategy for contacting subjects -selection of statistical tools -presentation of the findings

Pre-Experimental Designs for Description

Descriptive research can provide data for monitoring and evaluating policies and programs. These designs are concerned with how to answer questions such as: -how many? -how much? -how efficient? -how effective? -how adequate? Cross-Sectional Design
A cross-sectional design is used for research that collects data on relevant variables one time only from a variety of people, subjects, or phenomena. The data are collected all at the same time (or within a short time frame).

A cross-sectional designs provides a snapshot of the variables included in the study, at one particular point in time. It may reveal how those variables are represented in a cross-section of a population. Cross-sectional designs generally use survey techniques to gather data, for example, the U.S. Census.

Advantages and Disadvantages of Cross-Sectional Designs

Advantages	Disadvantages
data on many variables	increased chances of error
data from a large number of subjects	increased cost with more subjects
data from dispersed subjects	increased cost with each location
data on attitudes and behaviors	cannot measure change
answers questions on who, what, when, where	cannot establish cause and effect
good for exploratory research	no control of independent variable
generates hypotheses for future research	difficult to rule out rival hypotheses
data useful to many different researchers	static, time bound

Longitudinal Designs

A longitudinal design collects data over long periods of time. Measurements are taken on each variable over two or more distinct time periods. This allows the researcher to measure change in variables over time. There are two different types of longitudinal designs: time series and panel.

A Time Series Design collects data on the same variable at regular intervals (weeks, months, years, etc.) in the form of aggregate measures of a population. For example, the Consumer Price Index (CPI), the FBI Uniform Crime Rate, unemployment rates, poverty rates, etc.

Time series designs are useful for: -establishing a baseline measure -describing changes over time -keeping track of trends -forecasting future (short term) trends Time series data are nearly always presented in the form of a chart or graph. The horizontal (or x) axis is divided into time intervals, and the vertical (y) axis shows the values of the dependent variable as they fluctuate over time.
Researchers inspect a time series graph to look for four types of patterns: -long term trends (increases or decreases over the whole time span); -cyclical variations (short-term, valley-to-valley or peak-to-peak cycles); -seasonal variations (due holidays or weather); -irregular fluctuations (none of the above). Advantages and Disadvantages of Longitudinal Designs

Advantages	Disadvantages
data easy to collect	data collection method may change over time
easy to present in graphs	difficult to show more than one variable at a time
easy to interpret	needs qualitative research to explain fluctuations
can forecast short term trends	assumes present trends will continue unchanged

Panel Designs collect repeated measurements from the same people or subjects over time. Panel studies reveal changes at the individual level, for example, when a particular person was employed or unemployed, or when they were on or off of welfare.

Panel data can show different patterns from time series data. For example, about 5% of the elderly are institutionalized at any one time, but it is not always the same people. So elderly people have a 20% chance of being institutionalized at some point.

Advantages and Disadvantages of Panel Designs

Advantages	Disadvantages
reveals individual level changes	difficult to obtain initial sample of subjects
establishes time order of variables	difficult to keep the same subjects over time
can show how relationships emerge	repeated measures may influence subjects behavior

Case Study Design

Case studies examine some phenomenon in depth, e.g., people, programs, policies, decisions, organizations, etc. Case studies are useful for learning about: -policies or programs with remarkable successes -policies or programs with ambiguous or unexpected outcomes -situations where actors have discretionary behavior (e.g., street-level bureaucrats) A case study weave together data from documents, archives, interviews, participation, observation, artifacts, etc. It attempts to document not only the "what" but also the "why."

Advantages and Disadvantages of Case Study Design

Advantages	Disadvantages
includes data from multiple perspectives	limited to contemporary phenomena
combines data from different sources	need direct access to subjects
	need diverse sources of information
	need skills in many techniques
	can be an intense experience
	difficult to replicate findings
	insiders can be biased
	outsiders can be naive
	difficult to draw boundaries

Focus Groups
Focus groups are a method of group interviewing for obtaining qualitative data. It is not so much a research design as a data collection method. More will be said about focus groups in the section on data collection.

Meta-Analysis
A meta-analysis is a quantitative analysis of a sample of existing research studies on a particular topic. It is used to draw conclusions about the topic from a range of studies, for example, identify aspects of a program associated with program success. A meta-analysis may also generate new hypotheses for future research.

Problems with doing a meta-analysis are: -locating suitable studies -studies may not all have the same dependent variable -only findings of statistical significance are usually published -different studies may have many dissimilar aspects making them difficult to compare

Control Over Sources of Invalidity in Designs for Description

Source	Case study	Cross-section	Panel	Time-series
Internal Validity
History	weak	weak	weak	weak
Maturation	weak	weak	strong	strong
Testing			strong	strong
Instrumentation		weak	?	?
Regression		weak	strong	strong
Selection	weak	weak	weak	strong
Mortality	weak		weak	strong
Design Contamination			?	strong
External Validity
Testing			weak	weak
Selection	weak	weak	weak	?
Experimental Arrangements			?	?
Multiple Interactions

How to Improve the Validity of Designs for Description

1. Case study design

2. One-group Pre-Test/Post-Test Design

3. Non-randomized comparison group Pre-Test/Post-Test Design

4. One-group Time Series Design

Another way to improve the validity of designs for description:

1. Case study design

2. Randomized Control Group Post-Test only design

3. Randomized Control Group Pre-Test/Post-test design

4. Control group Time Series Design

O1	O2	O3	X	O4	O5	O6
O1	O2	O3		O4	O5	O6

What type of research design collects data at two or more points in time from different samples?

In a cross-sectional study you collect data from a population at a specific point in time; in a longitudinal study you repeatedly collect data from the same sample over an extended period of time.

What type of study design investigates two or more variables?

Correlational researchattempts to determine the extent of a relationship between two or more variables using statistical data. In this type of design, relationships between and among a number of facts are sought and interpreted.

What type of research design is data collection?

Quantitative Research Design: Quantitative research is referred to as the process of collecting as well as analyzing numerical data. It is generally used to find patterns, averages, predictions, as well as cause-effect relationships between the variables being studied.

What are the 4 types of research design?

Now that we know the broadly classified types of research, Quantitative and Qualitative Research can be divided into the following 4 major types of Research Designs: Descriptive Research Design. Correlational Research Design. Experimental Research Design.