chapter 2 : Research enterprise of psychology(2)

Question 1

What are the two types of statistics?

Answer 1

Descriptive statistics and Inferential statistics.

Question 2

What is descriptive statistics and what are the key descriptive statistics?

Answer 2

Descriptive statistics are used to organize and summarize data.

The key descriptive statistics are the measures of central tendency, measures of variability, and the coefficient of correlation.

Question 3

Define the 3 measures of central tendency.

Answer 3

The median is the score that falls exactly in the centre of a distribution of scores.

The mean is the arithmetic average of the scores
in a distribution.

The mode is the most frequent score in a
distribution

Question 4

Why is the mean the most useful measure of central tendency?

Answer 4

In general, the mean is the most useful measure of central tendency because additional statistical manipulations can be performed on it that are not possible with the median or mode

Question 5

How can the mean be misleading at times?

Answer 5

The mean is sensitive to extreme scores in a distribution, which can sometimes make the mean misleading.

Question 6

Define variability and the measure for variability ?

Answer 6

Variability refers to how much the scores in a data set vary from each other and from the mean.

The standard deviation is an index of the amount of variability in a set of data.

Question 7

How is variability and standard deviation related to each other?

Answer 7

Standard deviation is the measure for variability. If the variability is great then the standard deviation will also be large and vice versa.

Question 8

What role does variability and standard deviation play ?

Answer 8

Estimates of variability play a crucial role when researchers use statistics to decide whether the results of their studies support their hypotheses.

The standard deviation is also useful in understanding the normal curve or normal distribution.

Question 9

What is a correlation coefficient and what does it indicate?

Answer 9

The correlation coefficient is a numerical index of the degree of relationship between two variables.

A correlation coefficient
indicates:

(1) the direction (positive or negative) of
the relationship
(2) how strongly the two variables are related.

Question 10

Differentiate between positive and negative correlation.

Answer 10

A positive correlation indicates that two variables co-vary in the same direction.

A negative correlation indicates that two variables co-vary in the opposite direction.

Question 11

Explain the strength of the correlation.

Answer 11

The coefficient can vary between 0 and +1.00 (if positive) or between 0 and –1.00 (if negative).

The closer the correlation to either –1.00 or +1.00, the stronger the relationship. Thus, a correlation of 0.90 represents a stronger tendency for variables to be associated than a correlation of 0.40 does.

Question 12

How do predictions depend on correlation?

Answer 12

As a correlation increases in strength (gets closer to either –1.00 or +1.00), the ability to predict one variable based on knowledge of the other variable increases.

Question 13

Is correlation equivalent to causation?

Answer 13

Although a high correlation allows us to predict one variable from another, it does not tell us whether a cause-and effect relationship exists between the two variable.

The problem is that variables can be highly correlated even though they are not causally related.

Question 14

What is inferential statistics and what is its role?

Answer 14

Inferential statistics are used to interpret data and draw conclusions. After researchers have summarized their research data with descriptive statistics, they still need to decide whether their data provide support for their hypothesis.

Question 15

What is the most common forms of statistical inference ?

Answer 15

The most common forms of statistical inference is referred to as null-hypothesis significance testing .

Step 1 : Assuming the null hypothesis is true, there will be no difference in scores between the experimental group and control group.

Step 2 : Do the experiment and use descriptive statistics to show that there is a difference.

Step 3 : rejection of the null hypothesis.

Question 16

What does Statistically significant mean?

Answer 16

When the probability of the observed findings are due to chance is very low, then a research is said to statistically significant.

Question 17

What are the flaws to look for when evaluating research?

Answer 17

1. Sampling bias
2. Placebo effect
3. Social desirability
4. Response set
5. Halo effect

Question 18

What is the sampling bias?

Answer 18

Sampling bias exists when a sample is not representative of the population from which it was drawn. (WEIRD :Western, Educated, Industrialized, Rich, and Democratic )

Question 19

What is the placebo effect?

Answer 19

Placebo effects occur when participants’ expectations lead them to experience some change even though they receive empty, fake, or ineffectual treatment.

Question 20

Define social desirability bias.

Answer 20

Social desirability bias, which is a tendency to give socially approved answers to questions about oneself.

Question 21

Define response set.

Answer 21

A response set is a tendency to respond to questions in a particular way that is unrelated to the content of the questions.

Question 22

Define replication and what is its importance.

Answer 22

Replication is the repetition of a study to see whether the earlier results are duplicated.

The replication process helps science identify and purge inaccurate findings.

Question 23

What is experimenter bias?

Answer 23

Experimenter bias occurs when a researcher’s expectations or preferences about the outcome of a study influence the results obtained.

Question 24

How can experiementer bias be neutralized?

Answer 24

The double-blind procedure is a research strategy in which neither participants nor experimenters know which participants are in the experimental or control groups.