RS11 - Inferential statistics and probability

Question 1

Null hypothesis

Answer 1

Estimating that there will be no significant difference.

Question 2

Experimental hypothesis

Answer 2

Estimating that there will be a significant difference.

Question 3

Calculating probability

Answer 3

The likelihood of one of more events happening
Number of events / possible outcomes.
Outcome of two plus things: multiply
Outcome of one or another: add

Question 4

Statistical significance

Answer 4

The results did not occur due to chance.

Question 5

Alpha levels

Answer 5

0.05 or 0.01 - the chance of the results being significant.

Question 6

Confidence intervals

Answer 6

An interval that will include the unknown true parameter value.

Question 7

Type 1 error:

Answer 7

False positive: Wrongly rejecting the null hypothesis.

Question 8

Type 2 error:

Answer 8

False negative: Wrongly accepting the null hypothesis.

Question 9

Z scores (to calculate probability)

Answer 9

(Score - mean scores) / SD

Then look up Z score on table to find probability/area under curve.

Question 10

Standard error

Answer 10

SD / square root of sample size

Question 11

Central limit theorem

Answer 11

States that non-normal data has an approximately normal distribution.

Question 12

Skewed data

Answer 12

Lack of symmetry in the distribution of scores

Question 13

Negative skew

Answer 13

The mean and median are smaller than the mode

Question 14

Positive skew

Answer 14

The mean and median are larger than the mode

Question 15

Testing skewness

Answer 15

Skewness / standard error of skewness

If = / > 1.96 the skewness is significant.

Question 16

Kurtosis

Answer 16

The steepness or shallowness.

Question 17

Leptokurtic

Answer 17

Steep curve: positive kurtosis value

Question 18

Mesokurtic

Answer 18

Normal curve: zero kurtosis value

Question 19

Playkurtic

Answer 19

Flat curve: negative kurtosis value

Question 20

Outlier

Answer 20

Cases that have very different data values from the majority of cases in the data set.
If <80 an outlier has a standard score of +/- 2.5
If >80 an outlier has a standard score of +/- 3.0

Question 21

One tailed hypothesis

Answer 21

State the direction of the prediction - scores must fall in the top/bottom 5% depending on direction stated.

Question 22

Two tailed hypothesis

Answer 22

Do not state a direction in the prediction - scores must fall in the top or bottom 2.5%.