QUIZ 1 CH 1 & 2

What is the singular word for data?

datum

In science, the clearest way to isolate cause-effect relationships is to conduct a(n):

experiment.

A _____ allows researchers to display how many times each score occurs

frequency histogram

A graph that contains single points that are connected with a line is called a

frequency polygon

One person in a group of 10 people is 10 times older than any of the other members. With respect to age, it is most likely that the majority of group members are younger than the group's:

mean

The average score is also called the:

mean

In a skewed distribution, which is the BEST measure of central tendency to use?

median

The ___ is the score that is located in the middle of al scores

median

The _____ is the score that occurs most often in a data set.

mode

A _____ distribution is symmetrical and has a bell shaped curve.

normal

In a _____ distribution, the mean, median, and mode are all the same number.

normal

inferential statistics

numbers calculated from a distribution of scores to provide evidence supporting or opposing a hypothesis.

descriptive statistics

numbers calculated from a. distribution of scores indicating the central tendency (average) and the variability (amount of scatter around average)

A _______________ correlation indicates that two sets of scores tend to rise or fall together (for example, height and weight). A(n) _______________ correlation indicates that two sets of scores have an inverse relationship, which means that as one goes up, the other goes down (for example, time spent brushing teeth and tooth decay).

positive; negative

p-level

probability of finding a difference that is equal to or greater than what was actually measured, assuming that the null hypothesis is true

The _____ is the difference between the highest and lowest scores in a distribution.

range

What are the two common measures of variability?

range and standard deviation

If different researchers get consistent results from testing a hypothesis, the results are said to be

reliable.

The ________________ is a computed measure of how much the scores vary around the mean score.

standard deviation

Measures of _____ describe whether the values in a data set are spread out or clumped together.

variability

null hypothesis significance testing (NHST)

way of evaluating results by comparing the observed outcome to what would be expected if the null hypothesis is true

effect size

way of measuring the strength of a result; yielding a number that indicates the difference between two values; not affected by sample size

statistical significance

whether a research result differs sufficiently from what would be expected from chance alone due to random variations in behavior.

T or F Experimentation is the only appropriate way to conduct research?

False

T or F If a statistical test yields a p-level of .02, researchers using the NHST approach could conclude that the results are statistically significant, because there is only 2 percent probability that the outcome was due to chance

False

In the following data set, what is the mode? 3, 7, 8, 4, 4, 5, 9, 10, 6, 2

4

In the following data set, what is the median? 3, 7, 8, 4, 4, 5, 9, 10, 6, 2

5.5

In the following data set, what is the range? 3, 7, 8, 4, 4, 5, 9, 10, 6, 2

8

sample

A group of people or animals whose behavior is measured; this group is drawn from a larger population and the sample results are usually generalized to the population.

Population

A group of people or animals whose behavior is of interest to researchers; from this group one or more samples are selected for measurement.

correlation coefficient (r)

A statistic that indicates the precise numeral relationship between two variables; r can range from -1.0 to +1.0

T or F If a statistical test yields a p-level of .12, researchers using the null hypothesis significance testing approach would accept the result as a statistically significant effect

False

T or F If the mean score for Group A is at least 2 or 3 points higher than the mean of Group B, we can conclude that the difference between the groups is statistically significant.

False

T or F a p-level of less than .05 indicates that the probability of the outcome being due to chance is less that 5%

False

How do correlations help us make predictions?

Correlational research indicates how related one thing (such as self-esteem) is to another (such as depression). If the two variables are associated (correlated), then knowing the level of either one will help us predict the other.

Manipulation of the experiment means that:

all variables are controlled for, except the one being tested.

You are a school psychologist who administers the Wechsler Intelligence Scale for Children (WISC) to all sixth graders before they enter junior high. You notice that the intelligence scores have a smaller standard deviation than when you administer the WISC to children in your consulting practice. Why?

The community in your consulting practice is more diverse than the one in the school.

Why does correlational research help us make predictions, yet not explain cause-and-effect relationships?

The only information provided by correlational research is whether two variables are related—so whether one variable predicts the other. But this type of research tells us nothing about the direction of that relationship—nothing about why the variables are related or what is causing the relationship. For example, correlational research may tell us that happy parents tend to have happy children, but it does not tell us why. It could be because (1) having happy parents makes for happy children, (2) happy children make for happy parents, or (3) parents and their children share happiness-disposing genes.

T or F After the mean performance for two different groups has been calculated, if the 95% confidence intervals for those two menas do not overlap, researchers could conclude tat the difference between the groups was probably a reliable effect- a real difference

True

T or F Many researchers do not believe the NHST is an appropriate way to evaluate research outcomes

True

T or F Naturalistic observation is time consuming and could invade a persons privacy?

True

T or F One disadvantage of a survey is the possibility that participants might not answer the questions truthfully.

True

T or F case studies provide an in depth view of one persons behavior but the results might not generalize to others

True

T or F researchers consider a result to be statistically significant if there is a low probability that the outcome was due to chance

True

An in-depth observation of a small sample or single individual is an example of which research method?

a case study

mean

a measure of central tendency by adding all the scores and then dividing by the number of scores.

standard deviation

a measure of variability, indicating how tightly the scores are clustered around the mean.

descriptive research

a method of research designed to measure and describe a behavior without manipulating it.

Experimentation

a method of research that manipulates an independent variable to measure its effect on a dependent variable while controlling the other relevant variables.

correlational research

a method of research that measures two or more variables and explores the relationship between them

confidence interval

a range of scores calculated such that there is a specific probability (usually .95) that the value of interest actually falls within the range.

null hypothesis

a statistical assumption about the absence of an effect ( no difference between two values)

survey

a type of descriptive research in which participants report their own behavior or attitudes.

naturalistic observation

a type of descriptive research in which researchers directly observe behavior in its natural setting , without interference

case study

a type of descriptive research that studies an individual or small group in a detailed intensive way.

Which BEST describes a data set?

all raw scores make up a data set

A data set with two modes is called a

bimodal distribution

Measures of _____ describe the scores in the middle of a distribution.

central tendency

The mean, median, and mode are all measures of

central tendency

What are two types of measures numbers can be grouped into?

central tendency and variability

Mr. Brown has gathered evidence that the self-esteem of students is negatively correlated with their typical levels of anxiety. Before he uses this evidence to conclude that self-esteem reduces anxiety, Mr. Brown should be reminded that:

correlation does not prove causation.