Statistics Flashcards

1
Q

What is the purpose of the students T-test?

A

To find out if the difference between means is significant.

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2
Q

When is the value significant for a t-test?

A

If the value of t is GREATER THAN or EQUAL to the critical value, the difference between the two means is significant and you can REJECT the null hypothesis.

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3
Q

If I want to know if the difference between 2 means is significant what statistical test should I use?

A

T - test

If the value of t is GREATER THAN or EQUAL to the critical value, the difference between the two means is significant and you can REJECT the null hypothesis.

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4
Q

What is a null hypothesis?

A

A statement that says that there will be no significant difference / correlation between the things you are measuring. Purpose of statistical tests is to disprove the null hypothesis.

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5
Q

Define standard deviation.

A

Standard deviation shows the ‘spread of data around the mean’

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6
Q

Is it better to use standard deviation or range to evaluate data?

A

Standard deviation because SD is less affected by anomalous results

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7
Q

From standard deviation values you can plot error bars on a graph. If error bars overlap, what does this mean?

A

There is no significant difference between data values.

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8
Q

What does the Hardy-Weinberg principle predict?

A

It predicts that the frequencies of alleles in a population wont change from one generation to the next, but is only true under certain conditions.

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9
Q

What are the assumptions of the Hardy-Weinburg principle?

A

Assumptions:
Population must be large
There must be random mating/fertilisation
No migration
No mutation
No selection pressures ( no allele must be favourable/more beneficial

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10
Q

What is the purpose of the Chi-squared test.

A

Purpose: If you wanted to compare observed vs expected frequencies

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11
Q

Is there a difference between the frequency of different bird species at 2 different sites?
What statistical test should I use

A

Chi-squared
because you are comparing frequencies between groups

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12
Q

When is the value for Chi-Squared significant?

A

If your value for Chi-Squared is EQUAL TO or GREATER THAN the critical value, there is a significant difference between expected and observed and you can REJECT the null hypothesis.

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13
Q

If the standard deviation is small what does that tell us about the data?

A

The data is more consistent

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14
Q

When would I use Spearman’s Rank Correlation Coefficient?

A

To test for correlation between two variables variables

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15
Q

What does Spearman’s Rank Correlation Coefficient tell you?

A

It shows strength and direction of a correlation (from -1 to +1)
Use critical value table
IF calculated value GREATER or EQUAL TO the critical value then we can REJECT the null hypothesis there is a significant correlation.

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16
Q

What does standard error show?

A

Shows how accurate the mean is