Statistical Analysis

Question 1

Describe the different types of statistics

Answer 1

Descriptive–summary of raw values, describes a samples characteristics

Inferential–used to infer something about a population based on a sample’s characteristics (answer research question!)

Question 2

What are measures of central tendency?

Answer 2

Central tendency=one value that best represents entire group of scores. Mean, median, mode

Question 3

What are measures of variability?

Answer 3

variability=how scores differ/how much each score differs from the mean. Range, standard deviation, variance.

Question 4

What can a range be used for?

Answer 4

Gives an idea of how far apart scores are from one another

Question 5

What is a standard deviation?

Answer 5

average amount of variability in a set of scores. Average distance from the mean.

Question 6

What is variance?

Answer 6

the square of the standard deviation

Question 7

confidence intervals

Answer 7

a range of values around a mean that are believed to contain with a certain probability (ex 95%) the true value of that statistic

Question 8

correlation coefficient

Answer 8

measured the relationship between variables. How the value of one variable changes when the values of another variable changes. Range from -1.0 to +1.0 .

Absolute value =strength. +-=direction

Question 9

What is the strength of correlation for different correlation coefficients?

Answer 9

1=perfect
.7-.9=strong
.4-.6=moderate
.1-.3=Weak

Question 10

What is direct correlation?

Answer 10

variables change in the same direction (positive relationship)

Question 11

What is indirect correlation?

Answer 11

variables change in the opposite direction (negative relationship)

Question 12

What is a type I error?

Answer 12

False positive. Reject null when null is true.

Question 13

What is a type 2 error?

Answer 13

False negative. Failing to reject to null when null is false.

Question 14

What is alpha?

Answer 14

the probability of committing a type 1 error. What value is chosen before study is conducted to determine if statistical significance is present .

Degree of risk you are willing to take to have a false positive.

Question 15

Which type of error is focused more on minimizing?

Answer 15

Type 1 error. Balancing act between each type of error, type one error is more detrimental to make.

Question 16

What is a p value?

Answer 16

level of significance found after data was collected (probability value). {Probability of getting a false positive.
p

Question 17

What is statistical significance?

Answer 17

the likelihood a relationship b/w variables is caused by something more than random chance

Question 18

What are the steps in hypothesis testing (computing t-test statistics)?

Answer 18

1. Statement of null and research hypothesis
2. Set the level of risk (type 1 error) associated w/ null hypothesis (alpha)
3. Selection of appropriate test statistic
4. Computation of the test statistic value
5. Determination of the value needed for rejection of the null hypothesis (critical value, p value)
6. Compare obtained value and critical value
7. Decision.

Question 19

What is a t-test?

Answer 19

compares the differences between 2 means

Question 20

What are the different types of t-tests?

Answer 20

Dependent/paired (each case in one sample has a corresponding member in the other sample ex: pretest, posttest)

Independent t-test (two independent samples)

Question 21

What is ANOVA?

Answer 21

analysis of variance. Compares the amount of variability between groups with the amount of variability within groups. F test F(number of groups-1, participants).

1=differences between groups not significant. As F value increases, more likely not due to chance

Question 22

What is regression?

Answer 22

Statistical analysis, estimates relationship among variables

Question 23

What is R2?

Answer 23

proportion of variance in the dependent variable that can be explained by the independent variable. Positively biased, use adjusted R2.

Question 24

What are the types of regressions?

Answer 24

Linear regression: relationship b/w a DV and one IV

Multiple regression:
relationship b/w a dependent variable and two or more IV

Question 25

effect size

Answer 25

measure of a findings importance. size or magnitude.

Question 26

what is practical significance?

Answer 26

usefulness or practical application for the real world

Question 27

treatment efficacy

Answer 27

impact of treatment under well controlled and somewhat artificial conditions

Question 28

treatment effectiveness

Answer 28

impact of a treatment as it is actually administered in the “real world” of clinical practice. Ex: generalization

Question 29

WHat is social validity?

Answer 29

effects large enough to be noticed by naive observers