Planning Research Part 1Method, Participants, Instruments & Ethics

Kathy-ann Hernandez, Ph. D.Spring 2007

Participant Selection

Whom to select?

How to select?

How many to select?

Sampling Terms Random sampling/Probability

Every individual in the population of interest has an equal chance of being in the sample

Biased sampling/Non Probability some individuals from the population

of interest have a greater chance of being selected than other individuals

Sampling Procedures Sampling Procedures

Probability/Random Physical Mixing Process Random Number Table Systematic Random Sampling

Non-probability Sampling/non random sampling

Convenience or Accidental Sampling Purposive sampling

Biased Sampling

QL and QN Sampling Procedures

Quantitative Methods Simple Random Sampling Stratified Random Sampling Systematic sampling Cluster Sampling

Qualitative Methods Purposive sampling Criterion sampling

Convenience Sampling

Population vs Sample

Select by physically mixing or use table of random numbers

Stratified Sampling

Stratified random sampling used when we have subgroups in our population that are likely to differ substantially behavior.

Create separate strata and select randomly from each stratum. (gender, age groupings)

Stratified Proportionate Sampling

Proportionate sampling can be used with stratified sampling. Select individuals from each stratum based on the proportion they comprise of the population. Ex. 400 (M) ; 500 (F) - select 10% from each group.

Systematic Sampling

Select every nth person

Cluster Sampling

Cluster sampling is useful when it would be impossible or impractical to identify every person in the sample. Instead of sampling 10% of EU students, sample 10 % of the classes randomly.

Non probability/non random sampling

Convenience or Accidental Selecting a sample because it is easily

accessible and reasonably representative of the population of interest.

Purposive Sampling Handpicked individuals because they have

characteristics of interest

Criterion Sampling Clear criteria established for identifying

participants

Convenience Sampling

Convenience Sampling

Looks like cluster sampling, but clusters are not selected at random

Purposive Sampling

Purposive sampling targets a particular group of people.

Types of Purposive Sampling

Random Purposive Sampling Case sampling

Typical and extreme or deviant

Intensity sampling Maximum Variation sampling Homogenous sampling Opportunistic sampling Stratified Purposive sampling Snowball sampling

Instrumentation

How do I measure my variable of interest?

Where can I find instruments?

Can I create an instrument?

Instruments Use instruments used in Previous

Research Locate instruments from databases

ETS Tests in Print Buros Mental Measurement Yearbook

Begin thinking about creating your own instrument

Issues in Devising New Instruments

QN Validity- accuracy

Judgmental, criterion-related, and construct validity Reliability- consistency

Number of items, correlation coefficients QL

Credibility – accuracy member checks; triangulation of sources

Dependability – control of subjectivity Triangulation of instruments

Handout