Unit one test Flashcards
define statistics
the science of collecting, organizing, summarizing, and analyzing information to draw conclusions or answer questions.
what is a sample
a subset of the population that is being studied
what is a parameter
a numerical summary of a population
what is a population
the entire group of individuals to be studied
what is an individual
a person or object that is a member of the population being studied
what is qualitative data/variables & what does it measure
qualitative variables allow for classification of individuals based on some attribute or characteristic. Qualitative data are observations corresponding to a qualitative variable.
what is a statistic
a numerical summary based on a sample
what is the process of statistics
- identify the research objective
- collect data needed to answer the questions
- describe the data
- perform inference/ form conclusions
what is a continuous variable
a quantitative variable that has an infinite amount of possible values
what is quantitative data/variables & what does it measure
quantitative variables provide numerical measure of individuals. quantitative data are observations corresponding to quantitative variables
what is a discrete variable
quantitative variable that has a countable number of possible values
define nominal measurement
a variable is at the nominal level if the values of the variable name, label, or categorize.
define ordinal measurement
Has the properties of the nominal level and the naming scheme allows for the values of the variable to be arranged or ranked.
define interval measurement
has the properties of the ordinal level of measurement and the differences in the values of the variable have meaning.
**A value of zero in the interval level of measurement does NOT mean the absence of the quantity.
what is a case control study
require individuals to look back in time
define ratio measurement
has the properties of the interval level of measurement and the ratios of the values of the variable have meaning.
**A value of zero in the ratio level of measurement DOES mean the absence of the quantity.
define simple random sampling
if every possible sample of size n has an equally likely chance of occurring
what is a cross-sectional study
collect info about individuals at a SPECIFIC point in time, or lover a short period of time
define cluster sampling
obtained by selecting all individuals within a randomly selected collection or group of individuals
what is the difference b/w an observational study and a designed experiment
an observational experiment, the researcher observes behavior without trying to influence the study. in a designed experiment, the researcher intentionally changed the value of the explanatory variable.
define stratified sampling
obtained by separating the population into nonoverlapping groups called strata and then obtaining a simple random sample from each stratum
what is a cohort study
first identifies a group of individuals to participate in the study (the cohort)
they are observed over a LONG period of time
define systematic sampling
obtained by selecting every kth individual from the population
what is/why shouldn’t we use convenience sampling
a convenience sample is one in which the individuals in the sample are easily obtained.
– any studied that use this generally have suspect results
what is response bias
when the answers on a survey do not reflect the true feelings of the respondent.
what is non-response bias
when individuals selected to be in the sample who do not respond to the survey have different opinions from those who do.
how do you calculate relative frequency
take the frequency pf a category and divide it by the sum of all frequencies
what is sampling bias
the technique used to obtain the individuals to be in the sample tends to favor one part of the population over another.
what is under coverage
the proportion of one segment of the population is lower in a sample than it is in the population.
why do bars touch in a histogram
each interval starts from where the other ends (1-2.5, 2.6-3)
when do you use mean
Mean is best used for a data set with numbers that are close together.
what are the types of distribution
frequency distribution, relative frequency distribution,
when do you use median
for skewed distributions or distributions with outliers
when do you use mode
to summarize categorical variables
what is range
The range generally gives you a good indicator of variability when you have a distribution without extreme values
what is sample z score (formula and usage)
what is population variance
a measure of dispersion that determines how far each data point is from the population mean.
what is sample variance
the type of variance that is calculated using the sample data and measures the spread of data around the mean
