What is a population?
is any group in which a researcher is interested. A population can be large, such as all registered voters in San Joaquin County, or small such as all registered voters at San Joaquin Delta College.
What is a sample?
it is a smaller group culled from a population.
What is a statistic?
scores from a sample.
Descriptive statistics do what?
they summarize and describe data. For example, an average would be a descriptive statistic.
(Descriptive statistics are large numbers with data)
Inferential statistics do what?
they generalize from a population to a sample (inferring the sample is representative of the population)
What is a frequency?
the number of individuals or cases; its symbol is f.
What is a percentage?
indicates the number per hundred who have a certain characteristic; its symbol is P or %.
What is a proportion?
is a part of one signified by a fraction or decimal.
Scales of measurement are?
- N ominal (NAMING)
- O rdinal (ORDERING)
- I nterval (NO ZERO POINT)
- R atio (ZERO POINT)
(NAMING) A word scale of measurement listing by classification e.g. gender, race, age, etc.
(ORDERING) A word scale of measurement listing by some degree of order or ranking e.g. mild, moderate, severe
(NO ZERO POINT) A number scale of measurement noting equal distance with no meaningful zero point e.g. SAT scores from 200-800
(ZERO POINT) A number scale of measurement noting equal distance with a meaningful zero point e.g. weight lost or gained, dollars in pocket
A frequency distribution ...?
shows how many individuals had each score, either individually or by score intervals
The symbol X stands for...?
A cumulative frequency ...?
indicates how many individuals are in
a given score interval
- start at bottom with lowest score
- add next line up from f
- add from frequency all the way up.
- Top cf should be equal the sum of the f
Formula for percentage is...?
take f and divide by N
Formula for cumulative percentage...?
take cf and divide by N
Rounding off numbers are as follows:
- .075000 = .08 (to the nearest even #)
- .065000 = .06 (to the nearest even #)