Research design

Baseline A Treatment B Baseline A
O-O-O-O-O-X-X-X-X-X-O-O-O-O-O-O

Nice. Can you also elaborate in notation?

This design needs multiple observations of a single individual. The target behavior of a single individual is established over time and is referred to as a baseline behavior. The baseline behavior is assessed, the treatment provided and then the treatment is withdrawn.

Great.

I am happy to share with you! The last but not least is Single-Subject Designs. Let take A-B-A Single-Subject Design as an example.

Thanks a lot.

Sure. This involves random assignment of participants to 4 groups. It’s a special case of a 2X2 factorial design. Pre-tests and treatments are varied for the four groups. All groups receive a post-test.
Group A R------O------X------O
Group B R------O--------------O
Group C R --------------X-----O
Groupd D R---------------------O

I see. Can you elaborate more about it?

No. We still have Solomon Four-Group Design.

That’s all for different kinds of True Experimental Designs?

Yes you are right.
Group A R------X------O
Group B R--------------O

This is the case.

I heard about it and it’s popular. This design controls for any confounding effects of a pre-test. The participants are assigned to groups randomly. The treatment is only given to experimental group. We measure both groups in post-test.

You are welcome! The second one is Post-Test-Only Control-Group Design.

Thank you very much for your explanation.

Yes absolutely!

Let me try to illustrate by notations. Is it…
Group A R------O------X------O
Group B R------O---------------O

This design needs random assignment of participants to 2 groups. Both groups are administered both a pre-test and post-test but the treatment is for experimental Group A.

What does it mean?

The first one I want to talk about is Pre-Test-Post-Test Control-Group Design.

Thanks for your reply!

Yes, apart from pre-experimental and Quasi-experimental designs, there are True Experimental and Single-Subject Designs.

Are there any other types of research designs?

Sure. Please see below
Group A O--O--O—O--X--O--O--O—O
------------------------------------------------
Group B O--O--O--O--O--O--O--O--O

Can you express more clearly by using notations?

Its modification in which two groups of participants, not randomly assigned, are observed over time. A treatment is administered to only one of the groups (i.e., Group A).

What’s it?

Yes, the last but not least is Control-Group Interrupted Time-Series Design.

I see. Thank you so much! Any others?

Yes. It can be expressed as:
Group A O—O—O—O—X—O—O—O—O

I remember that we record measures for a single group both before and after a treatment.

Yes it is.

Is Single-Group Interrupted Time-Series Design also a kind of Quasi-Experimental Design?

Yes. You are right.

Yes…Is it
Group A O------X------O
-----------------------------
Group B O---------------O

It’s a popular approach to quasi-experiments. Experimental group (A) and control group (B) are selected without random assignment. Both of them take a pre- and post-test and only the experimental group receives the treatment.

Yes! I used it before.

First, Nonequivalent (Pre-Test and Post-Test) Control-Group Design.

I learnt several years ago but I’m not quite familiar with them.

Shall we talk about Quasi-Experimental Designs?

Yes please.

Yes actually I just mentioned some of them. If you are interested, I can write more here.

The above designs are ‘pre-experimental designs’. Are there any kinds of research designs?

My pleasure.

Great. Thank you very much for giving lots of examples!

The exception is that the nonequivalent comparison group received a different treatment.
Group A X1------------O
----------------------------
Group B X2------------O

Could you explain more?

We use the same procedure as the Static Group Comparison I have just mentioned as above, with an exception.

Oh, what is it?

Last but not least, Alternative Treatment Post-Test-Only With Nonequivalent Groups Design.

Thank you very much…

It is used after implementing a treatment. Researchers choose a comparison group and provides a post-test to both the experimental and comparison group(s) after the treatment.
Group A X ------------O
----------------------------
Group B ---------------O

What is it for?

Next, Static Group Comparison or Post-Test-Only With Nonequivalent Groups.

Nice. Any others?

The next one is One-Group Pre-Test-Post-Test Design which includes a pre-test measure followed by a treatment and a post-test for a single group.
Group A 01 ------X------02

Thank you very much!

Yes of course!

May I know more about the other types?

First, One-Shot Case Study. This design involves an exposure of a group to a treatment followed by a measure.
Group A X ------------O

Sure.

You are welcome. Now I am going to explain research designs in detail.

I see. Thank you very much for your illustration in advance.

You will see that there is a separation of parallel rows by a horizontal line. It indicates that comparison groups are not equal or equated by random assignment. No horizontal line between the groups displays random assignment of individuals to treatment groups.

Okay 

And random assignment is indicated with a symbol R.

I see…

The left-to-right dimension refers to the temporal order of procedures in the experiment. It is indicated with an arrow sometimes.

Yes. Yes…

X’s and O’s in a given row are applied to the same specific persons. X’s and O’s in the same column or placed vertically relative to each other, are simultaneous.

Ok…

O is what we can observe or measure on an instrument.

Yes…

X indicates an exposure of a group to an experimental variable or event and we are going to measure the effects.

Sure, thanks a lot.

Yes, but before I list some example, let me use the notations to illustrate the designs.