W10 Data Analysis II asynch.

Question 1

Define Inferential statistics

Answer 1

• next step after you have collected and summarized data

- used to make inferences from a smaller group of data to a possibly larger one

Question 2

what is a population?

Answer 2

a complete collection of all elements (scores, people, etc.)

Question 3

what is a sample?

Answer 3

A subset of elements drawn from a population

Question 4

How can you alleviate the problem of needing a large sample?

Answer 4

By selecting samples and extrapolating what was found

Question 5

What are we looking for in a representative sample?

Answer 5

• same sampling distribution (b/w sample and population of interest)
• similar sample mean and population mean
• similar measures of central tendency and dispersion (b/w sample and population)

Question 6

what is the goal of using a sample?

Answer 6

to generalize some parameters for a population based on what is learned from the sample

Question 7

what is an univariante analysis?

Answer 7

analysis of one variable….duh

Question 8

what is a bivariante analysis?

Answer 8

• describes relationship/association b/w two variables
• test relationship b/w dependent and independent variable
• how independent influence dependent variable
• anaylsis of two variables…duh

Question 9

what are the common types of bivariante analysis ?

Answer 9

• scatter plots
• correlation coefficient
• regression anaylsis

Question 10

define correlation, what is another name for it?

Answer 10

• bivariante anaylsis that measures strength of association b/w 2 variables and direction of relationship
• bivariante correlation

Question 11

what is a pearson correlation coefficient?

Answer 11

a numerical index that reflects the relationship b/w 2 continuous variables

Question 12

what are the directions of a relationship?

Answer 12

• positive (+ correlation coefficient)

- negative (- “ “)

Question 13

what is the strength of relationship?

Answer 13

the value of the correlation coefficient
- ranges b/w -1 to +1
- used to describe strength of relationship
(higher value = stronger relationship)

Question 14

What is regression analysis? What is it also known as?

Answer 14

aka the line of best fit

• minimizes distance b/w each individual point and the regression line
• enables predictions- how well x can predict y through the creation of the regression line

Question 15

picking the right statistical test depends on…

Answer 15

nature of the question being asked and form of the null hypothesis

• Example: do you want to look at the difference between 2 groups or the relationship between 2
  variables?
• these 2 situations will result in different statistical approaches, but both will result in test of
  null hypothesis using specific test of statistical significance

Question 16

identifying the most appropriate statistical method is…

Answer 16

dependent on number of variables and type of data involved

• # of variables: univariate, bivariante, multivariante
• types of data: continuous, categorical

Question 17

what is a chi- square? give an example.

Answer 17

2 categorical variables (each 2 or more levels)

- Eg. are hypertension and obesity status independent of one another?

Question 18

what is logistic regression? Give an example.

Answer 18

1 categorical DV(BP) (only 2 levels)
1 or more categorical IVs
- Eg. what are the odds of developing hypertension (yes/no) for each race after controlling for gender?

Question 19

Define confidence interval. What is it used to express?

Answer 19

1. communicates how accurate our estimate of the outcome/parameter is likely to be
2. range researchers are sure that true parameter lies somewhere b/w that range
   - if experiment conducted over again, estimate expected to be within this range

Question 20

The higher the confidence level, the greater…?

Answer 20

they are that relationship b/w variables (bivariante/multivariante) is not due to chance or other reason

Question 21

Researchers need to pick a confidence level that will describe…?

Answer 21

how certain they are that the estimate will fall within a selected range

Question 22

Define probability of error

Answer 22

-always chance of error
-risk associated with not being 100% correct
95% confident is association
5% experiment due to chance

Question 23

Define P-value

Answer 23

probability that a test statistic would be as extreme as or more extreme than observed if null hypothesis were true