practical stuff

Question 1

What is a null hypothesis?

Answer 1

A hypothesis that states there is no stastical significant difference between 2 variables.

Question 2

What are the 3 stats tests used?

Answer 2

1. Chi squared
2. T-test
3. Spearman’s rank correlation

Question 3

When is the chi squared test used?

Answer 3

to find the differences between observed and expected data is due to chance

Question 4

When is the T-test used?

Answer 4

looking for differences between mean values

Question 5

When is spearman’s rank correlation used?

Answer 5

looking for associations between different

measurements.

Question 6

why are straight lines drawn between points on a

graph?

Answer 6

when it is not possible to predict the intermediate values

Question 7

what points to mention when describing a graph?

Answer 7

1. general, overall trend

2. peak of data

Question 8

why is a pen not used to draw the origin line in chromatography?

Answer 8

ink and pigments would mix

Question 9

describe how chromatography is used to separate pigments after pigments are applied

Answer 9

1. placed in solvent with the origin line being above the solvent
2. remove before the solvent reaches the top

Question 10

describe how a sample from a plot of land is selected at random

Answer 10

1. make grid of plot
2. use random generator
3. to generate co-ordinates

Question 11

why are logarithmic scales used?

Answer 11

when there is a large range of quantities

Question 12

why are data loggers used?

Answer 12

1. more accurate
2. can measure to a greater no. decimal places
3. Data logging can be carried out 24 hours a day, 365 days of the year.
4. No need to have a person present.
5. Time intervals for collecting data can be very frequent and regular

Question 13

conclusion from chi-squared

Answer 13

if the calculated value of chi-squared is larger than the crititcal value at p=0.05,
then there is less than 5% probability that the differences between the observed and expected data are due to chance
and so the difference is significant.
Therefore, we reject the null hypothesis

Question 14

suggestion when a toxic/harmful form of medication needs to be used

Answer 14

use small amounts