Psychology: Stats

Question 1

What is Nominal data?

Answer 1

• Represented in the form of categories
• The most basic type of data
• Can count number in each category e.g. number of boys and girls in a year group
• Variables are non-numeric (can’t be ranked in order)
  e.g. What is your favourite food?

Question 2

What is Ordinal data?

Answer 2

• Data is ordered in some way
• The data does not have equal intervals
• Subjective
• Scores can be ranked in order but gaps between scores are not equal
• None standardised test are also ordinal

Question 3

What is Interval data?

Answer 3

• Data is based on numerical scales which are meaningful and have equal units (intervals)
• E.g. time, temperature, weight
• Most precise form of data
• Objective

Question 4

What is meant by Inferential statistics?

Answer 4

Tells us if the results we have are likely to be due to chance or due to a real effect

Allows us to draw inferences from our experiments and accept or reject our hypothesis

Question 5

What does P < 0.05 mean in words?

Answer 5

There is a 5% probability that the results found are due to chance

Question 6

Is P < 0.05 do we accept or reject the experimental (alternative) hypothesis?

Answer 6

We can accept the experimental Hypothesis

Question 7

What does P > 0.05 mean in words?

Answer 7

There is above 5% probability that the results found are due to chance

Question 8

Is P > 0.05 do we accept or reject the experimental (alternative) hypothesis?

Answer 8

We reject the experimental Hypothesis

Question 9

Why do psychologists use the 0.05 level of significance?

Answer 9

Because it means there is a 95% chance that the results are right

Question 10

What is meant by a type 1 error?

Answer 10

When we accept the alternative / experimental Hypothesis when in fact the results are due to chance

Question 11

What is meant by a type 2 error?

Answer 11

When we reject the alternative / experimental Hypothesis when in fact the results are due to the independent variable

Question 12

If we use the p<0.01 level in a study, is a type 1 or type 2 error more likely?

Answer 12

Type 2

Question 13

If we use the p>0.01 level in a study, is a type 1 or type 2 error more likely?

Answer 13

Type 1

Question 14

What are the 3 conditions (reasons) for choosing a statistical test?

Answer 14

• Difference or correlation
• Design of the study (independent measures (unrelated), repeated measures, matched pairs (related))
• The level of measurement

Question 15

Sign Chart

Answer 15

Title column Top -
IRC: Independent, Repeated Measures, Correlation
Title column Side -
NOI: Nominal, Ordinal, Interval

Chi-squared Sign test Chi-squared

Mann-whitney Wilcoxon Spearman’s Rho

Unrelated t test Related t test Pearson’s r

Cats Sing Cool Music Whilst Sitting Under Rainy Porches

Question 16

What is meant the Calculated Value?

Answer 16

Each test involves taking the data collected in the study and doing a set of calculations as directed in the test. Eventually a single static will be arrived - this is calculated value

Question 17

What is meant by the Critical Value?

Answer 17

• To decide if the calculated value is significant, the value has to be compared to another number that is found in a table of critical value

1. Value of N - number of participants minus the 0
2. Level of significance
3. On or two tailed test

Question 18

Be able to write a conclusion by comparing the calculated value to the critical value (see examples on showbie)

Answer 18

As the calculated value of …. is higher/lower/equal to the critical value of …… at the p<0,05 level of significance, we can accept/reject the experimental/alternative hypothesis and conclude that there is a less than/greater than 5% probability the results are due to chance.