Unit 0-Statistics

Question 1

Hypothesis

Answer 1

Represents the proposed answer to the experimental question

Question 2

Independent Variable

Answer 2

The variable ring manipulated to test the hypothesis

Question 3

Dependent Variable

Answer 3

the variable being affected and changed

Question 4

Control Group

Answer 4

The group that the experimental group is being compared to and is not exposed to the independent variable

Question 5

Positive Control

Answer 5

A control that tests that the experiment is working and has a known result

Question 6

Negative Control

Answer 6

A control that should not change and provides the baseline

Question 7

Controlled Variables

Answer 7

Variables that ensure that any observed effects are due to the independent variable and not other variables

Question 8

Reproducibility and Repeatability

Answer 8

More replicates, large sample size, confirmation of results via other researchers

Question 9

Tips about writing an experiment

Answer 9

Be brief and only state the main parts

Question 10

Graphing

Answer 10

1. Choose the correct graph (bar = categorical and line = continuous numerical)
2. Labeling the axes properly (x-axis = IV and y-axis = DV)
3. Scaling Axis (equal tick marks, label each tick mark, leave room for adding error bars)
4. Graph Precisely

Question 11

Bar Graph

Answer 11

Shows visual summary of how a data set is spread across various categories
Not continuous numerical data

Question 12

Scatter Plot

Answer 12

Allows you to establish relationships between two variables
Can draw trend line (line of best fit) to form a line graph

Question 13

Line Graph

Answer 13

Used to represent changes over time
Want to see changes in slope
No line of best fit

Question 14

Normal Curve

Answer 14

Describes most natural phenomena

Question 15

Does science usually work with populations or samples?

Answer 15

Samples

Question 16

Precision

Answer 16

Degree of closeness of the measurements with each other
AKA repeatability and reproducibility error

Question 17

Accuracy

Answer 17

Degree of closeness of the measurements to the target value
AKA bias error

Question 18

p=

Answer 18

probability value
Likelihood something occurs by chance

Question 19

Variability

Answer 19

More consistent data, the more confidence we have in it and a tool for predictions

Question 20

Standard Deviation measures…

Answer 20

Precision

Question 21

Standard Deviation

Answer 21

Absolute measure of dispersion of a series
Higher standard deviation = less confidence
square root of the sum of the squared values of the difference between the value and the mean divided by degrees of freedom

Question 22

Standard Eror

Answer 22

Tests reliability of data
Standard deviation in repeated samples from a population bc standard deviation only measures one dataset
Standard deviation divided by sqaure root of sample size
Small number = closer to true mean (more values)

Question 23

2SEM

Answer 23

Gives us 95% confidence

Question 24

If error bars overlap then…

Answer 24

There is not a statistically significant difference between the two
SD differs between each bar

Question 25

Null Hypothesis

Answer 25

Originally stated Hypothesis that indicates that there is no relationship between the IV and DV Any observed difference is due to chance or normal patterns

Question 26

Alternative Hypothesis

Answer 26

Indicates that there is a relationship between IV and DV and we reject the null hypothesis

Question 27

Statistical Significance

Answer 27

When data sets meet statistical criteria to determine that the observed differences are unlikely due to chance alone

Question 28

Degrees of freedom

Answer 28

Indicates how many independent peices went into a calculation n-1

Question 29

Critical Value

Answer 29

a threshold that the calculated chi-square statistic must meet or exceed to be considered statistically significant

Question 30

Chi Square Value X^2

Answer 30

Number calculated by formula to compare to the critical value observed values minus expected values, square each value, divide by expected values, and add the numbers If greater than critical value = significant difference If less than critical value = no significant difference

Question 31

Theory

Answer 31

General explanation of the world that is supported by a great amount of evidence and observations

Question 32

Ability of atoms to combine with others atoms depends largely on...

Answer 32

Valence electrons

Question 33

Covalent Bond

Answer 33

A bond formed when two atoms share a pair of electrons

Question 34

Electronegativity

Answer 34

Ability of an atom to attract electrons

Question 35

Polar vs. Nonpolar

Answer 35

Polar = electrons are distributed unequally due to different electronegativities Nonpolar = electrons are equally distributed due to similar electronegativities

Question 36

Ion

Answer 36

Electrically charged atom caused by an extra electron or a lost of an electron

Question 37

Ionic Bond

Answer 37

A chemical bond is formed when two opposte charged ions associate withe ach other