Exam 1: Non-Experimental Designs Flashcards
Straw-Man Hypothesis
• A null hypothesis that is not plausible and no one would actually believe
The null should be something that could plausibly happen!
Non-Experimental Design
- No manipulation of variables
- Examine effects of existing differences (Can be quantitative or qualitative)
• Goals
- Observe, describe, document behavior or characteristics
- Examine relations among behavior or characteristics
- Compare characteristics and how that impacts behaviors
ex: pure-tone averages are what they are, you cannot manipulate them
Types of Non-Experimental Designs
1) Descriptive
• Surveys, polls, case studies, prevalence studies
2) Relationship
• Correlational, predictive
3) Comparative
• Case-control, group comparisons
4) Causal-Comparative or Cohort
• Impact of causal factors over time
Descriptive: Surveys
1) Participants asked a series of questions
2) Who are the participants?
3) What are the questions?
• Types
• Sequence
• Valid/reliable
4) How will you give it?
• e.g., oral, written
Types of Survey Questions
- Yes/No
- Categorical
- Rating Scale
- Cumulative Response
- Open-Ended
Cumulative responses- you can choose more than one answer
Advantages of Surveys
- Easy to test and score
- Can test large numbers of people
- May be standardized (Provide basis for what is typical)
- Reliable but not necessarily valid
if you get a large enough group of people you can get a standardized score
PROMIS: assessment of these dimensions in survey form
within these are sub-measures that are really standardized
so you get a real sense of what’s normal or standard in a population
You can administer sub-components of this (i.e. fatigue) for projects
Disadvantages of Surveys
• Difficulty of crafting the questions
Leading questions
- Should concerned parents use a home program as part of their child’s speech therapy? - Implying that you should use this program- subtle implication of the value of the behavior
• Social desirability
• Ambiguity
- E.R. rate pain on scale from 0-10
• Voluntary/nonresponse bias
- Not a true sense of people and their beliefs b/c you would only get people who had time to answer their landline
Descriptive: Case Study
- Intense observation of an individual (person or setting) to understand their behavior
- Case studies can help us pose the right questions, but they may not be enough…Either need a lot of time points for 1 kid or a lot of kids
- Tensions between gathering evidence in a natural settings and having as much experimental control as possible
- May be quantitative or qualitative
- Focused or broad
- Intrinsic: understand the particular entity
- Instrumental: study a particular case that represents a larger phenomenon
- Collective: collect data on several instrumental cases
Piaget (1896-1989)
- In depth case studies of his own children
- Child reasoning, cognition, and perception of the world
- Used to conceptualize stages of development
- Children are “little scientists”
- Representation of reality is built on analyzing evidence, constructing theories about the world
- Errors accumulate, forcing a new representation
Object Permanence
Object Permanence
• Knowledge that objects exists when no longer in sight
• If you cover an object with a blanket, child believes it
disappears
• Piaget found that until 9-12 months of age, children lack object permanence
• Why children cry when mom leaves and peak-a-boo is fun
Correlations and Regressions
1) Correlation
• Two variables that vary along a dimension (not groups)
• Examine if the extent of one relates to the extent of the other
* studying the relationship between two variables - do a correlational analysis to determine the strength of the relationship
2) Regression
• Two or more variables
If a researcher is studying the relationship between several variables, do a regression analysis to determine the strength of the relationship and also which variables have the most predictive power.
** correlation does not establish causality
• Examine measures close in time or use one or more to predict the future occurrence of another
Comparative
- Groups: Examine the impact of existing differences between two or more groups on a measure of skill/characteristic
- Demographics
- Disorder vs. controls: Case-control study
- Example case-control study
- Comparing adolescents with SLI and typically developing peers on a measure of narrative language ability (Wetherell et al., 2007)
Example: Comparative vs.
Correlational
• Issue: Do different personality types differ in their use of hand gestures while communicating?
• Personality survey measured degree of extroversion/introversion
• Videotaped a conversation with each participant and counted the
number of hand gestures they made
• Option 1) Classify people as either introverted or extroverted and compare the two groups
• Option 2) Use their scores along the continuum of extrovert-to- introvert and see if this correlates with hand gestures
Advantages/Disadvantages of
Comparative/Correlation studies
- Comparative
- Assumes everyone is either one or the other category
- Problem if unequal sample sizes
- Correlational
- The degree to which people are one vs. the other
- Problems of restricted range, skewed sample (extreme participants)
Cross-sectional
Cross-sectional
Cross-sectional studies are descriptive studies (neither longitudinal nor experimental); a type of observational study that analyzes data collected from a population, or a representative subset, at a specific point in time.
- Groups may differ on factors besides age
- Faster to run
- Attrition not a factor
- Participants are naïve
- No concern that having taken part in the study at one age might change what the person would do at a later age
Longitudinal Research
An individual or group is followed for some extended period of time from about 1 year to 25 years. Longitudinal research is usually non-experimental, however, in some cases it can be experimental.
• Better control for other differences between groups; Slower to run; More participant drop out (attrition)
- Order effects
- If participants learn from being in the experiment, older kids will always do better than younger kids
Longitudinal: child development— you might want more than 5 years to look at an outcome
Causal-Comparative or
Cohort Studies
A cohort study is a type of longitudinal study that allows researches to study the emergence of disorders over time or study the long term effects of a treatment.
- researchers are investigating existing differences while obtaining information about several variables (not just the primary variable under study)
• Permit stronger inferences about possible cause/effect: e.g., risk factors
- can be retrospective or prospective
• Causal-Comparative: Obtain several measures per participant in order to control for possible alternative explanations
Cohort Study
- Longitudinal design
- Prospective (concurrent)
- Current information to predict future status
- e.g., Framingham Heart Study
Prospective- relationship between cholesterol and heart disease; people chosen to be studied before developing heart disease
• Retrospective (historical)
• How do past records explain present status • e.g., Carter et al. (2003): compared speech/
language impairment of children who had been exposed to malaria (vs. not) 2 yrs prior
Do people who get CIs feel self-conscious about them? - what non-experimental design to use?
not comparing them to another group
survey them
- When do children start using the past-tense ending correctly?
- Uses word-completion tasks, like Joey like to skip; he skips every day. Yesterday he _____.
what non-experimental design to use?
Relationship either cross-section or longitudinal
What non-experimental design to use?
Do people who see student clinicians feel more or less satisfied than those who see professional clinicians?
Comparison of 2 groups
What non-experimental design to use?
What is the relationship between amount of hearing loss and extent of hearing handicap?
correlational
Qualitative Research
- Data may include verbal statements, direct quotes, excerpts, open- ended responses, detailed descriptions of behavior, etc.
- Researchers rely on inductive reasoning to formulate a theory - Data is collected to identify trends, themes –> theory
- Natural environments/situations
- Small sample sizes, lot of time observing a fewer number of people or samples
Naturalistic Observation
- Ethology: the study of naturally occurring behavior
- Method: making detailed observations of animal or humans in their natural settings
- Konrad Lorenz
- Argued that one cannot understand animal behavior without the context of its environment