Research Methods L13 - 15

Question 1

How can the results that appear in tables be described as?

Answer 1

• Descriptive statistics (Measures of central tendency/dispersion)
• Not raw scores

Question 2

Measures of central tendency:

Answer 2

• Mean
• Mode
• Median

Question 3

Measures of Dispersion:

Answer 3

• Range
• Standard deviation

Question 4

Types of graphs:

Answer 4

• Bar chart
• Histogram
• Line graph
• Scattergraph
• Distribution Curve

Question 4

Bar chart:

Answer 4

• Represents frequency of each item
• Space between bars
• Nominal data

Question 5

Histogram:

Answer 5

• Area under bars must equal to frequency represented
• No gaps between bars
• Ordinal/interval data

Question 6

Line graph:

Answer 6

• Connected by lines to show change over time
• IV on x axis, DV on y axis
• Ordinal/interval data

Question 7

Scattergraph:

Answer 7

• Relationship between co-variables
• Closer the points, stronger the correlation

Question 8

What shape should the frequency of the measurements reflect in most data sets and what is this known as?

Answer 8

• Bell-shaped curve
• Normal distribution curve

Question 9

Do the ends of a normal distribution curve touch x axis and why is this the case?

Answer 9

• No
• More extreme scores are always theoretically possible

Question 10

What are the names of asymmetrical normal distribution curves?

Answer 10

Skewed distributions

Question 11

Descriptive stats:

Answer 11

Measures of central tendency/dispersion

Question 12

Inferential stats:

Answer 12

Generalising one result to the population (inference)

Question 13

Level of Statistical Significance:

Answer 13

• The level at which the decision is made to reject the null hypothesis in favour of the experimental hypothesis
• States how sure we can be that IV will have an effect on DV and it is not due to chance

Question 14

Chance:

Answer 14

Something that has no real cause and just occurs

Question 15

In which situation would the experimental hypothesis be accepted and the null hypothesis rejected and what is this called?

Answer 15

• If there is a real difference between both sets of data
• Results are significant

Question 16

Probability:

Answer 16

Numerical measure determining whether our results are due to chance or whether there is a real difference between the sets of data

Question 17

What is the standard level of significance used in psych and why is this number used?

Answer 17

• p < 0.05 (5% results are due to chance , 95% certainty there is real difference)
  Reasons for use:
• Not too strict or too lenient, but is a middle and fair value of significance
• Minimises chances of making Type 1 or Type 2 error

Question 18

In psychology, what is the highest and lowest level of significance possible and what numbers are they?

Answer 18

• Highest, most lenient: p < 0.10 (10% results are due to chance , 90% certainty there is real difference)
• Lowest, most strict: p < 0.01 (1% results are due to chance, 99% certainty there is real difference)

Question 19

Often when is p < 0.01 used?

Answer 19

When research findings are critical eg. testing effect of drug

Question 20

Why is a sign test used?

Answer 20

• Looking for difference between data
• Looking at paired/related data –> could come from repeated measures/matched pairs design
• Nominal data

Question 21

Steps of sign test:

Answer 21

1) State hypothesis (either one or two-tailed)
2) Subtract one column from another and work out the difference
3) Note down the sign of difference (positive/negative)
4) Count the number of positive and negative signs
5) Choose the lower value to be S value
6) Find out how many pps there are (ignore any blanks/differences of zero)
7) Find critical value in table using N, probability and whether it is one/two tailed
8) If s ≤ critical value, results are significant

Question 22

How would the results of a sign test be written out?

Answer 22

The results of the experiment are significant. The calculated value for S is lower than/equal to the critical value of …. when p < 0.05 (usually unless question says otherwise) under a two-tailed hypothesis.