Lecture 5 - Descriptive Studies

Question 1

What are the three types of measurement

Answer 1

1) Nominal
2) Ordinal
3) Continuous

Question 2

What are the two types of continuous measurment?

Answer 2

• interval

- ratio

Question 3

What is the nominal scale based on? examples?

Answer 3

the classification of an observation according to the group that it belongs.

Ie: gender, political party, marital status

Question 4

What is the ordinal scale based on? examples?

Answer 4

the classification of an observation according to its relationship to other observaitons

Ie: poor-fair-good rating scale

Question 5

What is the interval scale characterized by? examples?

Answer 5

equal units of measurement. The distance between any two numbers is known

NOTE: zero point is arbitrary

I.e. - farenheit scale centigrade temperature scale

Question 6

What is the ratio scale characterized by? examples?

Answer 6

equal units of measurement and a true zero point at its origin

I.e. mass, time

Question 7

Whats a population? Whats a sample? What do they represent

Answer 7

Population - all individuals in a study
sample - a portion of the individuals in a population studied to find trends in the population

Populations are constants not variables
samples are variable

Question 8

What are the three measures of central tendency?

Answer 8

1) Mean
2) Median
3) Mode

Question 9

When is the mode best utilized to analyze central tendency?

Answer 9

Mode is most useful when used with nominal measurement but can be used with all scales

Question 10

When is the median best utilized to analyze central tendency?

Answer 10

probably most useful with the ordinal scale but can be used with higher order scales

Question 11

When is the mean best utilized to analyze central tendency?

Answer 11

Most useful with interval or ratio scales

Question 12

What are the measures of variability/dispersion?

Answer 12

1) Range
2) Interquartile range
3) Variance
4) Standard deviation
5) Coefficient of variation
6) standard error of the mean

Question 13

What are the measures of variability/dispersion?

Answer 13

1) Range
2) Interquartile range
3) Variance
4) Standard deviation
5) Coefficient of variation
6) standard error of the mean

Question 14

What is the range?

Answer 14

The difference between the largest and smallest measurment

Question 15

What is the interquartile range?

Answer 15

The range within the 75th %ile and 25th %ile of the gross data

Question 16

What is variance?

Answer 16

How much the gross data varies from the mean. Calculated by taking each individual data point minus the mean of the sample and then squaring that value. The result divided by the total number of data points -1 gives you the sample variance

Question 17

what is the standard deviation

Answer 17

the positive square root of the sample variance

Question 18

what is the coefficient of variation?

Answer 18

a unitless number that allows for the comparison of the percentage of spread of the data

Question 19

What is the central limit theorm?

Answer 19

A theory that states that a sample distribution will be bell shaped if the it is randomized and the sample is large enough (30-40)

Question 20

What is standard deviation a measure of? Standard error? similarities? differences?

Answer 20

Standard deviation is an estimate of variability of a certain data point from the mean, standard error is the same for a sample mean and population. Similar in that they both assess distance from the mean, different in that SD measures one point, and SE measures multiple

Question 21

What is a confidence interval?

Answer 21

the interval used to predict the probability of an event with a certain confidence. AKA 95% of the time this event will occur within 2 standard deviations from the mean