chapter 5 research and methods

Frequency Distribution

an orderly arrangement of scores indicating the frequency of each score or group of scores

class interval frequency distribution

a table in which the scores are grouped into intervals and listed along with the frequency of scores in each interval

qualitative variable

a characteristic that is defined by its presence or absence in a category ( use bar graph)

bar graph

a graph that uses vertical or horizontal bars to show comparisons among two or more items (nominal)

histrogram

a diagram consisting of rectangles whose area is proportional to the frequency of a variable and whose width is equal to the class interval. ( ratio, interval, ordinal)

Quatitative

data measured and has numerical value (histogram)

descriptive methods

case study
survey
naturalistic observation
(DON'T SHOW CAUSE/EFFECT)

archival research

method of research using past records or data sets to answer various research questions, or to search for interesting patterns or relationships

frequency polygon

graph of a frequency distribution that shows the number of instances of obtained scores, usually with the data points connected by straight lines ( ratio, interval, ordinal)

measure of central tendencies

a Number that means middle

Mean: Average
Median: Middle Number
Mode: Most common number

measure of variation

A measure used to describe the distribution of data

range

Standard deviation

Average deviation

standard deviation

a computed measure of how much scores vary around the mean score

average deviation

An alternative measure of variation that, like the standard deviation, indicates the average difference between the scores in a distribution and the mean of the distribution. X - mean

variance

standard deviation squared

Kurtosis

how flat or peaked a normal distribution is

Mesokurtic

normal curves that have peaks of medium height and distributions that are moderate in breadth

Playkurtic

distribution is low and flat because the scores are spread out

Leptokurtic

normal curves that are tall and thin, with only a few scores in the middle of the distribution having a high frequency

Postive skewed distribution

Most of the scores are bunched towards the left. The mode is to the left of the mean because the mean is affected by the extreme scores tailing off to the right.

negative skewed distribution

Most of the scores are bunched towards the right. The mode is to the right of the mean because the mean is affected by the extreme scores tailing off to the left.

z-score

a measure of how many standard deviations you are away from the norm (average or mean)

standard normal distribution

A normal distribution with a mean of 0 and a standard deviation of 1.

Probability

A number that describes how likely it is that an event will occur

hypothesis testing

the theory, methods, and practice of testing a hypothesis by comparing it with the null hypothesis. The null hypothesis is only rejected if its probability falls below a predetermined significance level, in which case the hypothesis being tested is said to have that level of significance.

ask about probability testing

Use descriptive statistics when

One is describing a complete a sample of scores or events

Use inferential statistics when:

Want to generalize from a sample of known scores to a population of unknown scores

one-tailed alternative hypothesis

only one direction of an effect or relationship is predicted in the alternative hypothesis of the test

two-tailed alternative hypothesis

The means of the groups being compared differ in any way

type one error

rejecting null hypothesis when it is actually true - a false positive

type two error

Wrongly accepting the null hypothesis

statical significance

A statical statement of how likely it is that an obtained result occurred by chance ( for the study to be valid must be less the 0.05)

descriptive statistics

describe distribution (minimum, maximum, mean, standard deviation)

inferential statistics

procedures for drawing conclusions about a population based on data collected from a sample

measure of variation

A number that indicates the degree to which scores are either clustered or spread out in a distribution

variance

the standard deviation squared

mail survey

a written survey that is self-administered

Telephone survey

survey conducted via telephone in which questions are read to the respondents

open-ended questions

questions for which respondents formulate their own responses

close-ended questions

questions on which respondents must choose from a limited number of alternatives

partially open-ended questions

closed-ended questions with an open-ended "other" option.

rating scales (Likert scales)

respondents rate on a numeric scale indicating the direction and strength of their response

stratified random sampling

a sampling technique designed to ensure that subgroups or strata are fairly represented

cluster sampling

a sampling technique in which clusters of participants that represent the population are used

convenience sampling

a sampling technique in which participants are obtained wherever they can be found and typically wherever is convenient for the researcher

quota sampling

a sampling technique that involves ensuring that the sample is like the population on certain characteristics but uses convenience sampling to obtain the participants

sampling bias

a tendency for one group to be overrepresented in a sample

interviewer bias

the tendency for the person asking the questions to bias the participant's answers

socially desirable responses

a response that is given because a respondent believes it is deemed appropriate by society

expectancy effects

narrative records

full narrative descriptions of a subject's behavior

checklist

a tally sheet on which the researcher

static item

type of item in which attributes that do not change are recorded

action item

type of item used to note the presence or absence of behaviors

qualitative research

a type of social research based on field observations that is analyzed without statistics

loaded question

a question that includes nonneutral

leading question

a question phrased in such a way as to suggest the desired answer; a lawyer may ask leading questions on cross-examination

double-barreled

a question that asks more than one thing

response bias

the tendency to consistently give the same answer to almost all of the items on a survey