chapter 2/week 2

Question 1

variability

Answer 1

the degree to which scores in a set of data differ or vary from one another
Central to the research process

Question 2

variability (list) - no variability no story

Answer 2

1. Psychology and other behavioral sciences involve the study of behavioral variability
   
   • Ex 1 - Dating
2. Research questions in all behavior sciences are questions about behavioral variability
   
   • Ex - Differences in dating behavior among generations?
3. Studies show be designed in a way that best allows the researcher to answer questions about behavioral variability
   
   • Ex - sample 80 people around 20, sample 80 people around 20; survey, t test, compare
4. The measurement of behavior involves the assessment of behavioral variability
   
   • Ex - how are we going to measure dating; commitment? Frequency of dating?
5. Statistical analyses are used to describe the amount for the observed variability in behavior

Question 3

Variability and Research steps

Answer 3

1. focus on variability
2. questions about variability
3. design for variability
4. measuring variability
5. statistical analyses for variability

Question 4

Variability and Research - 1. Focus on Variability

Answer 4

What is the source of variation?

Is it variation/change
- Across situations
- Among individuals
- Over time

Question 5

Variability and Research - 2. Questions about Variability

Answer 5

Identify what your research questions is about
- What varies
- To what extent can we predict variability in a certain behavior
- Why does it vary

Question 6

Variability and Research - 3. Design for Variability

Answer 6

Research should be designed in a manner that best allows the researcher to answer questions about behavioral variability

Think of your questions
- How does it vary
- Observation, correlational

- Under what circumstances does it vary 
 - Quasi-experimental 

- How can we control variability 
   - Experimental

Question 7

Variability and Research - 4. Measuring Variability

Answer 7

The measurement of behavior involves the assessment of behavioral variability

We measure behavior through operationalization of concepts

We assign numbers to behaviors such that the variability in the numbers reflects the variability in the behavior

No variability, no assessment

Question 8

Variability and Research - 5. Statistical Analyses for Variability

Answer 8

Statistical analyses are used to describe and account for the observed variability in the behavioral data

We use data analysis to answer questions about the variability in our data:
How much variability is there
What is it related to
What caused it

Question 9

An Illustration of Hypothesis Testing

Answer 9

General Hypothesis example – There is an association between one’s stress level and having to deal with contradictory views at once

Null Hypothesis example – there will be no association between having to deal with contradictory views and one’s general comfort level

Question 10

Two Types of Statistics

Answer 10

descriptive statistics
inferential statistics

Question 11

descriptive statistics

Answer 11

used to summarize and describe the behavior of participants in a study

Question 12

inferential statistics

Answer 12

used to draw conclusions about the reliability and generalizability of one’s findings

Question 13

How to capture variability in behavior using statistics?

Answer 13

range
variance
standard deviation

Question 14

range

Answer 14

difference between the largest and smallest scores (observed participant behavior) in a distribution

Question 15

variance

Answer 15

a statistic that takes into account all the scores when calculating the variability

a statistic used to indicate the amount of variability in participants’ responses

Question 16

standard deviation

Answer 16

the square root of the variance; generally easier to interpret

Question 17

how to calculate standard deviation

Answer 17

find the mean

subtract mean from each score (deviation)

Then square each of the values (the differences)

Calculate the total sum of the squares [add the squared values together]

Calculate the variance – divide the sum by the number of values present minus 1

take square root of the result

Question 18

why is Variance A Better Alternative ?

Answer 18

range doesn’t describe the distribution

We express the variability of the data using all the scores, not just the highest and lowest ones, with a statistic called the variance

Question 19

mean

Answer 19

the sum of a set of scores divided by the number of scores

Σyi / n

Question 20

variance and the mean (interpretation)

Answer 20

We assess the variability in a set of data by seeing how much the scores vary around the mean

If the scores are tightly clustered around the mean, then the variance of the data will be small

If the scores are more spread out from the mean, then the variance will be larger

Question 21

how to calculate variance

Answer 21

Calculating the mean of the data
Subtracting the mean from each score (deviation)
Squaring these differences or deviation scores
Summing these squared deviation scores
Dividing by the number of the scores minus 1

Question 22

statistical notion of variance

Answer 22

s² = Σ (y_{i} - ȳ)²(n-1)

Question 23

deviation

Answer 23

score:
- how the scores vary around the mean
- how each score differs from the mean

Question 24

positive deviation score

Answer 24

indicates that the participant’s response fell above the mean

Question 25

negative deviation score

Answer 25

indicates that the participant’s response fell below the mean

Question 26

normal distribution

Answer 26

normal curve split: 34.1%, 13.6%, 2.1%, 0.1% -3σ, -2σ, -1σ, mean/mu, 1σ, 2σ, 3σ

Question 27

total variance

Answer 27

the total sum of squares divided by the number of scores minus one Total variance = systematic variance + error variance

Question 28

systematic variance

Answer 28

the portion of the total variability in participants’ scores that is an orderly, predictable fashion to the variables the researcher is investigating This phrase refers to the part of the variation in participants' scores (or outcomes) that can be explained or predicted by the specific factors or variables the researcher is studying.

Question 29

error variance

Answer 29

the portion of the total variance in participants’ scores that is unrelated to the variables under investigation in the study; variance remains unaccounted for AKA - measurement error, experimental error --> Can mask or obscure the effects of the variables in which researchers are primarily interested in

Question 30

Distinguishing Systematic from Error Variance

Answer 30

Researchers use statistical analyses to partition the total variance of their data into systematic and error components The more error variance in the data, the more difficult it is to determine whether the variables of interest are related to variability in behavior Researchers try to **minimize error variance** as much as possible in order to detect the systematic variance in the data

Question 31

effect size

Answer 31

indicates the proportion of the total variance that is systematic variance A measure of strength of association - the strength of the relation between two variables Because the effect size is a proportion, it is easy to compare effect sizes across many different studies with different research strategies

Question 32

Assessing the Strength of Relations

Answer 32

If effect size = .00, then none of the variance in participants’ responses is systematic If effect size = 1.00, then all the variability in the data can be attributed to the variables under study The larger the proportion, the stronger the relationship between variables

Question 33

There are several indicators of Effect Size:

Answer 33

Correlational effect sizes: r-squared Group difference effect size: Cohen’s d Association among categorical variables: odd-ratio

Question 34

meta-analysis

Answer 34

a procedure used to examine every study that has been conducted on a particular topic to assess the relationship between whatever variables are the focus of the analysis Effect sizes allow us to compare across studies: meta-analysis By looking at effect sizes across many studies, a general estimate is calculated to reflect the strength of the relationship between the variables

Question 35

Research is a quest for Systematic Variance

Answer 35

All researchers are trying to account for (or explain) the behavioral variability they observe If there is no variability, there is no systematic variance and hence no story to be told