STATISTICS

Question 1

Mean

Answer 1

total / # of data points

most useful when data set does not have outliers or is not skewed to one extreme

Affected by extreme values or outliers

Question 2

Median

Answer 2

Middle Data Point

more helpful when there are outliers or data is skewed

Not as affected by extreme values or outliers

if there are two middle data points, the average of those two values is the median.

Question 3

Mode

Answer 3

Most occurring value in a data set

is possible for there to be more than one mode or no modes

use mode when the data are non-numeric or when asked to choose the most popular item (For example, you
ask 100 people “what is their favorite color?” The Mode would more useful than mean or median.

Question 4

Range

Answer 4

Largest value - smallest value = range

Question 5

Normal Distribution

Answer 5

When the data is equally distributed and has little to no skew.

When the mean, median, and mode are equal or nearly equal

Question 6

Positively Skewed

Answer 6

Mean being pulled by outliers in the positive direction

Question 7

Negatively Skewed

Answer 7

Mean being pulled by outliers in the negative direction

Question 8

Outlier

Answer 8

a point (value) that lies an abnormal distance from other points (values)

could also mean a point that doesn’t follow a trend in the data

can distort mean

Question 9

Accuracy

Answer 9

how close a measured value is to the actual (true) value

Question 10

Precision

Answer 10

how close the measured values are to each other

Question 11

Random Errors

Answer 11

Fluctuations of data in either direction

can be overcome by taking more data

could have accuracy but never have precision

Question 12

Systematic Errors

Answer 12

All of the data is off in THE SAME WAY

has precision but no accuracy

Question 13

Rounding

Answer 13

rounded value should not go beyond the precision of instrument that was used to record

Question 14

Percent Change

Answer 14

the amount of change relative to the original value

((Final – Initial) / Initial) * 100

Question 15

Absolute Average Deviation (AAD) (MAD)

Answer 15

the average distance between each data value and the mean

To Find AAD:
1. find the mean (average)
2. find the difference between each data value and the mean
3. take the absolute value of each difference
4. find the mean (average) of these differences

Question 16

Percent AAD

Answer 16

Quantifies the AAD relative to the mean.

(AAD / Mean) * 100

Question 17

T-Test

Answer 17

Assesses if the observed difference between means is due to chance or due to the independent variable

Question 18

p-value (in T-Test)

Answer 18

the probability (in percentage) that the observed difference in the means is not due to the the independent variable, but it is due to chance

The lower the p-value, the more likely that the observed difference is a result of the independent variable and not due to chance

Question 19

Scientists generally agree that a p=value of ____ or lower is low enough
to accept that the observed difference is not due to ____. This Also Disproves the ______.

Answer 19

0.05, chance, null hypothesis

Question 20

Null Hypothesis

Answer 20

a hypothesis that says there is no statistical significance between the two variables in the hypothesis

THE HYPOTHESIS THAT THE RESEARCHER IS TRYING TO DISPROVE

Question 21

When to use bar graph

Answer 21

Data is Discrete - this is data that can be counted and has a finite number of values. These values must be able to fall within certain classifications and are unable to be broken down into smaller parts

Examples:

The number of employees in your department

The number of new customers you signed on last quarter

Question 22

When to use line graph

Answer 22

Data is continuous - data has values that are not fixed and have an infinite number of possible values. These measurements can also be broken down into smaller individual parts.

Examples:

The height or weight of a person

The daily temperature in your city

Question 23

Elements of a Proper Graph

Answer 23

1. Title
2. proper style (bar, line, pie)
3. labeled axis (including units)
4. key: indicating independent variables (for example
   naming each of the bars by color)
5. line of best fit if appropriate, error bars if it is a bar graph with means
6. Caption

Question 24

Caption of a Graph

Answer 24

Describes the graph or table in enough detail for the graph or table to be understood in isolation for the text.

must include:
1. whether the graph shows raw data or means
2. Identifying error bars as AAD
3. sample size
4. number of replications

Example (see photo):

Rats were tested on their mass based on whether or not the received growth hormones. Data shown as mean +/- AAD. Sample Size = 6 Repetitions = 1.

Question 25

Factors that influence P-Value

Answer 25

1. Distance between the means
2. Spread of the data
3. Sample size