Biology Statistics Module

Question 1

What axis is the Dependent Variable plotted on?

Answer 1

Plotted on the Y axis

Question 2

What is the Independent Variable?

Answer 2

What the observer is changing in the experiment

Question 3

What axis is the Independent Variable plotted on?

Answer 3

Plotted on the X axis

Question 4

What type of data do bar graphs show?

Answer 4

Categorical data and discrete data

Question 5

What must you remember when plotting a bar graph?

Answer 5

SLTKB
S- Scale
L- Labelling
T- Title
K- Key
B- Bars

Question 6

What type of data do histograms show?

Answer 6

Continuous data

Question 7

What do line graphs show?

Answer 7

How one variable changes as another variable also changes.
It shows continuous data

Question 8

What do scatter graphs show?

Answer 8

One variable plotted against another one, allowing correlations to be identified

Question 9

Does correlation mean causation?

Answer 9

Correlation does not mean causation

Question 10

What does an axis break do?

Answer 10

Shrinks a large segment of data down and enhances readability

Question 11

What is the correlation coefficient range?

Answer 11

-1 to +1 where -1 means Strong negative correlation and +1 means strong positive correlation

Question 12

What are the two types of hypotheses and what do they mean?

Answer 12

Alternate and Null Hypothesis.
The alternate hypothesis states that there will be a statistically significant difference between the two variables. This means you predict something based on scientific theory.
The Null hypothesis states that there will not be a statistically significant difference between the two variables.

Question 13

How is the alternate hypothesis written?

Answer 13

I predict that there will be a statistically significant difference between X and Y. X will be ______ compared to Y. X therefore has _______ effect on Y. My results are unlikely to have occurred by chance.

Question 14

How is the Null hypothesis written?

Answer 14

I predict that there will not be a statistically significicant difference between X and Y. X will be ________ compared to Y. X therefore has no effect on Y. My results may have occured by chance.

Question 15

What is standard deviation?

Answer 15

Standard deviation measures the spread of the set of numbers, in effect the average distance of each number from the mean.

Question 16

What are the rules of standard deviation?

Answer 16

1. The bigger the standard deviation, the larger the spread of numbers.
2. A smaller standard deviation implies the numbers are closer together.

Question 17

What is the formula for standard deviation?

Answer 17

S.D= √(∑(x1−¯x)^2
/n-1
S.D= Standard deviation
∑=Sum of
¯x= mean
x= each number
n= how many numbers there are in a set

Question 18

When are unpaired T-tests used?

Answer 18

Used to compare the means of two unrelated groups.

Question 19

What is the unpaired T-test?

Answer 19

The unpaired T-test tells you the probability that a difference between two independent means is due to chance. It tells you if there is a statistically significant difference between two means.

Question 20

What is the formula for the unpaired T test?

Answer 20

(¯xA - ¯xB)
/ SQRT (S.D^2 A / nA) + (S.D^2 B / nB)
¯xA= mean of A
¯xB= mean of B
S.D A= Standard deviation of A
S.D B= standard deviation of B
nA= number of measurements of A
nB=number of measurements of B

Question 21

When is the Null hypothesis rejected in unpaired T-tests?

Answer 21

If the value for t exceeds a critical value.

Question 22

What is the formula for Degree of freedom?

Answer 22

DF= nA + nB -2