ch02 descriptive and inferential statics

Descriptive Statistics

**Because relationships are never perfectly consistent,
1)The purpose of descriptive statistics is to bring order to this chaos.
2)organizing and summarizing sample data so that we can communicate and
describe their important characteristics.

"Important characteristics"

* general understanding of the data without having to look at every simgle
score
* there is a precision cost to such summaries "generally", "around", or
"more or less"

**predict when a particular behavior will occur

REMEMBER: Descriptive statistic are used to summarize and describe the
important characteristics of sample data and to predict an individuals's Y
score based on his or her X score

Inferential Staticstcs

Thus, although technically descriptive statistics are used to describe samples, their logic is also applied to populations

Even we can not measure the population in practice, we can estimate the description of the population, based on the sample data

But remember we cann't assume that a sample is representative of the population. Before we draw any conclusion about the population we must 1st perform inferential statistics.

Inferenctial staticstcs are procedures for deciding whether sample data accurately represent a particular relationship in the population.

if the samples is "deemed represnetative", then we use the descriptive statics computed from the sample as the basis for estimating the scores that would be found in the population.

REMEMBER: Inferential staticstics are for deciding whether to believe what the sample data indicate about the scores that would be found in the population.

 

after we performing statistics we do the behavioral:
We interpret the results in terms of the

• underlying behaviors,
• psychological priciples,
• socialogical influences, and so on

that they reflect.