Summary Stats, Distributions, and Central Limit Theorem

Question 1

What is data reduction?

Answer 1

reduces bits of data

Question 2

Frequency distribution?

Answer 2

a chart that summarizes data in terms of the frequencies of a variable value

• a simple tally or chart
• can be used w/ continuous or categorical data. Bar chart is categorical. Histogram is continuous.

Question 3

Cumulative frequencies?

Answer 3

The totals broken up equal to the sum of a class;
Ex: 11100100 missing 0 (1=female; 0=male)
how many female?: 4/10= 0.4=40%
how many male?: 5/10= 0.5=50%
how many missing?: 1/10= 0.1=10%

Question 4

What is a relative frequency?

Answer 4

The ratio of frequency of a particular event to the total frequency
-how many times a value of data keeps occurring

Question 5

Frequencies can be computed for continuous variables T or F?

Answer 5

True

Question 6

Measures of central tendency?

Answer 6

• mode
• median
• mean

Question 7

Mode?

Answer 7

frequency of values

Question 8

Mean?

Answer 8

the average of values

Question 9

Median?

Answer 9

the middle value when all values are in order

Question 10

Measures of variability?

Answer 10

-range

Question 11

What is standard deviation?

Answer 11

the square root of the variance

-an indication of the dispersion of a variable

Question 12

Variance?

Answer 12

average squared distance from the mean

Question 13

Sample variance formula?

Answer 13

slide 54/78

Question 14

What is a distribution?

Answer 14

It describes how values for a certain

Question 15

standard deviation^2=

Answer 15

variance

Question 16

distribution of continuous variables

Answer 16

ex: percentiles, probabilities

Question 17

-25th percentile-
-50th percentile-
-75th percentile-

Answer 17

-first quatile
-second quartile (median)
-third quartile

Question 18

-10th percentile-
-25th percentile-
-50th percentile-

Answer 18

-data point which 10% falls below
-data point which 25% falls below
-data point which 50% falls below

Question 19

right skewed distribution implies what?

Answer 19

mean>median>mode

Question 20

left skewed distribution implies?

Answer 20

mode>median>mean; opposite

Question 21

sample distribution?

Answer 21

distribution of observed values in the sample
-sample mean and sample SD are denoted (x (w/ a hat on top), s)
they are stats or sample stats and describe the center and spread of this distribution

Question 22

population distribution?

Answer 22

distribution of possible values from a population
-pop. mean and SD are denoted
-they are parameters that describe the center and spread of this distribution

Question 23

sampling distribution?

Answer 23

distribution of a (sample) stat-especially, the distribution of x (w/ a hat on top)
-sample mean follows normal distribution w/ mean and standard deviation