MARKETING RESEARCH CHAPTERS 7: Descriptive Research Design: Survey and Observation 8 Experimentation

Descriptive Research Design: Survey The survey method is a structured questionnaire given to a sample of a population designed to elicit specific information from respondents. The survey has the following advantages: ease, reliability, and simplicity (the ease of removing the information from the structured questionnaire and putting the information into computerized form). The survey has the following disadvantages: respondents may be unable or unwilling to provide the information and it may be difficult to get a sampling frame to draw a representative sample.

Descriptive Research Design: Survey: Modes Telephone: Traditional and computer-assisted telephone interviewing Personal: in home, mall intercept, computer assisted personal interviewing Mail: mail panel, mail/fax interview Electronic: email or internet

Advantages and Disadvantages of Telephone Interviewing Interviews completed quickly No travel time Limited labor costs Sample control high Supervision from central location Response rate good Personal rapport difficult to achieve Respondents can escape easily Less tolerance for lengthy interviews

Advantages and Disadvantages of Personal Interviews In-home: Provides clarification to respondent Can use visual aids Easy to sample homes Respondents tolerate longer interviews Response rate good However people home now so difficult to find respondent at home Interviewer control difficult More social desirability problems Interviewers can influence answers-interviewer bias

Advantages and Disadvantages of Personal Interviews Mall Intercept: Respondent is already present in mall Research facilities in many malls Appropriate when there is a need to handle product Response rate good Social desirability issues Interviewer bias Limited data can be collected as people are in a hurry High cost

Advantages and Disadvantages of Personal Interviews Computer Assisted Personal Interview Holds respondents interest Can ask completed set of questions as computer automatically carries out skip pattern Computer administers interview Interviewer bias limited Useful when physical stimuli needed Good control of data collection Good response rate Social desirability issues Limited data High cost

Advantages and Disadvantages of Mail Methods Economical Can reach lots of people No personal contact so no interviewer bias Moderate to large amounts of data People can easily throw away the survey Low sample control Response rates very low Can result in non-response bias

Improving Survey Response Rates Prior notification Incentives (monetary and non-monetary) Follow-up Other facilitators of response such as reminders

Observation Methods Personal observation Mechanical observation

Advantages and Disadvantages of Observation Do not require conscious respondent input Interviewer bias control since observer only puts down what is observed Easier to use with pets and children Best applied to phenomenon that occur frequently or are of short duration We do not know why something is happening – subject to subjective analysis Not good for infrequent behavior or behavior of long duration (although anthropologists have used this method effectively living with people for long periods of time)

Causal Research Design: Experimentation What is the meaning of causality? Causality: when the occurrence of variable X increases the probability of the occurrence of Y To have causality: if the two events occur together one might cause the other, but one must actually precede the other, and there must be no other event that could cause the second event

Experimentation To actually show cause and effect, we must set up an experiment. An experiment is the process of manipulating one or more independent variables and measuring their effect on one or more dependent variables while controlling for extraneous variables. An independent variable is the cause of something and usually manipulated by the researcher The dependent variable is the effect of changes in the independent variable Experiments use test units: anything sampled or selected for an experiment.

Experimentation Continued We control for extraneous variables or other things than the independent variable that might affect the response of test units. The most usual way of controlling for extraneous variables is to use random assignment of test units to the experimental groups. There are often two types of groups in an experiment: control and experimental groups. The control group is the comparison group and the experimental group you will change in some way. You will then compare results between the two groups. Normally, you will DESIGN your experiments

Experimental Design We can use specific symbols help organize how we think about experimental design: X = The exposure of a group to some kind of change often called a treatment O= The process of observation or measurement of the dependent variable on the test units. R= The random assignment of test units to separate treatments or groups.

Experimental Design Continued Designs can be pre-experimental, true experimental, quasi-experimental, and what your book calls statistical designs although with the other designs it is possible to use statistics as well. Pre-experimental designs do not use randomization. One shot case study: X O1 One-group pretest-posttest: O1 X O2 Static Group Design: EG: X O1 CG O2

Experimental Design Continued True experimental designs use randomization which is one method for controlling for extraneous variables. Randomization means that you know the probability of selecting each test unit for a particular group.

Experimental Design Continued Pretest-posttest control group design: EG: R O1 X O2 CG: R O3 O4 The treatment effect is measured as the difference: (O2-O1)-(O4-O3). There may be a problem with this design although it is very common: interactive testing effects Posttest-Only control group design: EG: R X O1 CG: R O2 The treatment effect is: O1-O2

Validity in Experimentation Internal validity refers to whether the manipulation of the independent variables or treatments actually caused the observed effects on the dependent variables. Control of extraneous variables is a necessary condition for establishing internal validity. External validity refers to whether the cause-and-effect relationships found in the experiment can be generalized. To what populations, settings, times, independent variables, and dependent variables can the results be projected?

Extraneous Variables History refers to specific events that are external to the experiment but occur at the same time as the experiment. Maturation (MA) refers to changes in the test units themselves that occur with the passage of time. Testing effects are caused by the process of experimentation. Typically, these are the effects on the experiment of taking a measure on the dependent variable before and after the presentation of the treatment.

Extraneous Variables Instrumentation (I) refers to changes in the measuring instrument, in the observers, or in the scores themselves. Statistical regression effects (SR) occur when test units with extreme scores move closer to the average score during the course of the experiment. Selection bias (SB) refers to the improper assignment of test units to treatment conditions. Mortality (MO) refers to the loss of test units while the experiment is in progress.

Experimental Design Continued Quasi-experimental designs include time series designs where you look at changes in a variable over time.

Experimental Design Continued Statistical designs consists of a series of basic experiments that allow for statistical control and analysis of external variables. They offer advantages in that the effects of more than one independent variable can be measured, extraneous variables can be controlled, and designs can be used where each subject is measured more than once. Generally, these designs are called Analysis of Variance Designs. One type of this design is called factorial which we will discuss when we look at ANOVA (analysis of variance designs).