statistics part 1

Question 1

variability introduced due to either our measuring instruments not being precise enough or differences in how two different people read the measurement

Answer 1

observational or measurement variability

Question 2

variability that accounts for the fact that members of populations are simply different

Answer 2

natural variability/inter individual variability

Question 3

opposite of natural variability, occurs because we have assigned our population or sample to two or more treatment groups and then observe the variability between the groups

Answer 3

induced variability

Question 4

occurs when we take multiple samples from a population randomly. these samples will be different due to the randomness of the sampling process

Answer 4

sample variability

Question 5

observational studies, experimental studies,surveys

Answer 5

3 major types of ways to collect data

Question 6

collections of data from a population where variability is not induced by treatments but by the sample itself (sampling variability)

Answer 6

surveys

Question 7

collections of data from a population where assignment of individuals from the population into treatment groups is not under the control of those performing the study

Answer 7

observational studies

Question 8

in experimental studies individuals are assigned randomly to treatment groups in order to determine the effect of the treatment on the variability of the data. In these cases, the assignment, although random, is under the control of those performing the study

Answer 8

experimental studies

Question 9

is critical for being able to minimize variability due to sampling bias (error that results in a misrepresentation of a population)

Answer 9

why random sampling is important

Question 10

mena, median, and mode in a set of data

Answer 10

measures of central tendency

Question 11

used to break up data into fourths, and each contains 25% of the data

first quartile is median for lower half of the data, second quartile is the median for the entire set of data, third quartile is the median for the upper half of the data (3/4s of the data lies below the third quartile and one fourth lies above)

Answer 11

quartiles

Question 12

measures how the data is spread out & dispersed
look at the range, standard deviation (way to describe the difference between the mean and the values in the data set)

Answer 12

measure of dispersion

Question 13

population form & sample form standard deviation

Answer 13

2 forms of standard deviation

Question 14

used when the data being analyzed includes the entire set of possible data

Answer 14

possible form standard deviation

Question 15

used when the data is a random sample taken from the entire set of data

Answer 15

sample form standard deviation

Question 16

1 var stats ORDER (mean, sum of all data values, sum of the squares of data values)
Sx- Sample standard deviation
ox- the population standard deviation
n- number of values in the data set
minX- lowest data value
Q1- quartile 1
med- median
Q3- 3rd quartile
maxX- highest data value

Answer 16

stats on calc (1-var stats)

Question 17

Sx

Answer 17

sample standard deviation, only use when asked

Question 18

ox

Answer 18

population standard deviation, use unless asked for sample standard deviation

Question 19

lowest, q1, median, q3, highest

Answer 19

box and whisker plot

Question 20

normal distributions are symmetrical with a single central peak at the mean (average) of the data. the shape of the curve is descrubed as bell shaped with the graph falling off evenly on either side of the mean.

50% of the distribution lies to the left of the mean and 50% lies to the right of the mean

Answer 20

normal distribution & normal curve

Question 21

for a normal distribution, nearly all of the data will fall within THREE standard deviations of the mean:

68% of the distribution lies within one standard deviation of the mean

95% of the distribution lies within two standard deviations of the mean

99.7% of the distribution lies within three standard deviations of the mean

Answer 21

empirical rule

Question 22

68% of the distribution lies within one standard deviation of the mean

95% of the distribution lies within two standard deviations of the mean

99.7% of the distribution lies within three standard deviations of the mean

Answer 22

percentages to know

Question 23

68% of the distribution lies within ONE standard deviation of the mean

Answer 23

68% of the distribution lies within ONE standard deviation of the mean

Question 24

95% of the distribution lies within TWO standard deviations of the mean

Answer 24

95% of the distribution lies within TWO standard deviations of the mean

Question 25

99.7% of the distribution lies within THREE standard deviations of the mean

Answer 25

99.7% of the distribution lies within THREE standard deviations of the mean

Question 26

** you can ONLY use the normal curve for a question if it specifically says that the data is NORMALLY DISTRIBUTED OR STANDARDIZED

Question 27

• used to determine a particular data point’s percentile, which is the percent of the population less than the data point
• when calculating a percentile, ALWAYS use a lower bound of -100,000

-2nd var stats, plug numbers into set and then solve but the equation MUST say normal distribution

Answer 27

calculating percentiles (normalcdf)

Question 28

the complete set of all subjects that share a common characteristic that is being studied

Answer 28

population