Standard Deviation

Question 1

State four scales of measurement and give ex of each

Answer 1

Nominal ordinal ratio interval

Question 2

Discrete vs continuous

Answer 2

Discrete: measured in whole units or categories (like siblings) whereas continuous is measured along a continuum at any place beyond the decimal point (times in Olympics, etc). Continuous can be measured in fractional units.

Question 3

____ describe characteristics in a population, whereas ____ describe(s) characteristics in a sample

Answer 3

Parameters; Statistics

Question 4

Operational Definition

Answer 4

An Operational Definition is a description of some observable event in terms of the specific process or manner by which it was observed. DVs require an operational definition as they can often be measured in many ways.

Question 5

Experimental requires three things

Answer 5

Manipulation; randomization; comparison/ control

Question 6

Quasi-experimental

Answer 6

Quasi-independent variable but may lack control group

Question 7

T/F Qualitative Variables can be continuous or discrete

Answer 7

False - they can only be discrete

Question 8

Find the Real Range

Answer 8

1: one more than the difference between the largest and smallest number in a list of data. If smallest is 0 and highest is 75, real range is 76 (175-0 = 75, 75+1 = 76)

Question 9

Find interval width

Answer 9

Observed range divided by number of intervals. Recommended between 5 and 20 only - no more ranges.

Question 10

To construct frequency distribution, 3 steps

Answer 10

1 Find real range
2 Find interval width
3 Construct frequency distribution

Question 11

Four rules for frequency distributions

Answer 11

1 Each interval is defined w upper and lower boundary
2 Equidistant
3 no interval overlaps (same score can’t occur in more than one interval
4 all values are rounded to same degree of accuracy measured in the original data

Question 12

What is “degree of accuracy”

Answer 12

Numbers Rounded to same degree

Question 13

Define “Open interval” or “open class”

Answer 13

Interval with no defined upper or lower boundary

Question 14

What is recommended number of intervals that should be included in a simple frequency distribution?

Answer 14

5 to 20

Question 15

What is cumulative frequency?

Answer 15

A summary display that distributes the SUM of the frequencies across a series of intervals - (so like ascending sum)

Question 16

What is relative frequency?

Answer 16

Observed frequency divided by total frequency count - so (basically just a proportion from 0-1 so divide count by total - like if x shows up 2 out of 45 times, it’s relative frequency is .04)

Question 17

What is an ogive

Answer 17

Pronounced (Oh-jive)
Used to summarize cumulative percents of continuous data at the upper boundary of each interval. Always goes from 0-100. Page 53

Question 18

Frequency polygon qualities

Answer 18

Grouped data; dot-and-line graph where the dot is the midpoint of the interval , and the line connects each dot

Question 19

Name the statistical test you can use to determine if model is a good fit

Answer 19

Hosmer-Lemeshow

Question 20

Name 3 ways you can determine if the logistic regression model is a good fit

Answer 20

1) Statistical test: Hosmer-Lemeshow (h0=fit is good), but this breaks as #s get high
2) Standardized Deviance Residuals should be between -3 and 3 etc
3) ROC Curve (Receiver Operating Characteristics) Area under the curve, (AUC) graphical plot that visualizes the performance of measurement for classification problems at various threshhold settings - how much a model can distinguish between classes. (want high AUC)