Vocab list 2 test 1

• an objective way of interpreting a collection of observations.
• Types of statistics – Descriptive techniques – Correlational techniques – Differences among groups

generalization of results to some larger extent/group

• a group of participants,  treatments, or situations selected from a larger group
• a selection of people or items from the population
• easier/quicker to use

• refers to all people or items with a particular characteristic of interest
• the larger group from which a sample is taken

• i.e picking every 100th name in phone book
• select a sample for telephone interviewing by selecting every 20th name in the student directory

• Method of stratifying a population on some characteristic before random selection of the sample
• i.e picking 20 males from 1000 random 20 females from 1000 random

i.e assign id numbers to clients pick clients at random

Justification that the sample repressents some groups at large

• a single score that best represents all the scores
• Indication of the typical score in a data set
• – Mean – Median – Mode

• the degree of difference between each individual score and the central tendency score
• measures of how scores vary
• – Range – Interquartile range – Standard deviation

• an estimate of the variability of the scores of a group around the mean (Rmpa)
• measure of how much the score varies around the mean
• *spread of scores about the mean
• gives us the average amount by which the scores deviate from the mean

the square of the standard deviation

• Most frequently used measure of central tendency
• add all numbers divide by sum of participants
• influenced by extremes

middle of all scores in order

most frequent score occuring

• Highest- lowest
• variability score 

• Present an interval estimate of the population mean
• Indicates the interval within which we are confident the population mean will fall
• Centered around the sample mean
• Provies an expected upper and lower limit for a statistic at a specified probability level
• Can be represented in error bar charts

• Distribution of data in which the mean, median and mode are at the same point.
• and in which is from the mean includes
• Skewness – Kurtosis
• 68% of the scores 1+ from the means
• 95% 2+ from score and 99% is 1+

• Normal distribution Equal variances – Independent observations
• Test based on data assumptions of normal distribution  equal variances and independent observations

• Distribution is not normal
• any of a number of statistical techniques used when the data do not meet the assumptions required to perform parametric

• the probability of rejecting a false null hypothesis
• The probability of making a correct decision!
• Directly related to the probability of making a type II error

• description of the dirction of the hump of the curve of the data distribution and the nature of the tails of the curve
• *term that describes the position of the hump in the curve of a distribution is
• side to side
• Left positive skewness
• Right negative skewness

• Description of the vertical characteristics of the curve
• Whether the curve is more peaked or or flatter

• A criterion for significance is set
• This is usually a probability set at .05
• if our calculated p-value is less than the criterion for significance
• This is classed as ‘statistically significant’

The importance or practical significnat of an effect or relationship

Odds that a certain event will occer

• The probability that your results are due to chance or sampling error
• chance your results are due to chance or sampling error

• a statement of no difference or no relationship.
• statistical hypothesis that assumes that there is no difference among the effects of treatments
• i.e There is no difference between the vocabulary scores of average- and high-ability students.

level of probability set by the experimenter before the study

• rejecting the null hypothesis when its true
• probability of making a Type I error is denoted by the alpha (α) 
• researcher claims that there is a difference between treatments (i.e., rejects the null hypothesis) when there really is no difference

• accepting the null hypothesis when its true
• a Type II error is denoted by the beta (β) level

Magnitude of a type 2 error

the number of participants in the study being evaluated or planned

• the outcome of a study typically expressed in standard deviation units
• standardized value that is the difference between the means divided by the standard deviation 
• Meaningfulness The size of the difference (Cohen’s d) 
• the strength of the relationship (r2)

variability of the sampling distribution

statistical techniques which helps us describe data

statistical techniques devised to allow us to generate from our data to populations

values which divides data set into exactly 4 equal parts

the average of the squared deviates from the mean

sampling where the population is divided into smaller identifiable clusters and one or more of these cluster are then randomly selected. Participation are then randomly selected from smaller cluster to take part in a study

sampling from those people who are available at a particular time and place

a sampling technique where individuals who have taken a part in a study provide detail of people they know who might also be willing to participate

sampling which relies on participants coming forward to volunteer to take part in a study usually in response to an advertising

bias in the estimation of population paremeters that arise from using samples

statistical descriptions of populations

description applied to samples

same as probality odds of something happening

a distribution of a scores which is symmetrical peaked in the middle, is bell shaped and equal on both sides of the peak

• Suggests a difference or relationship but not the specific direction of these
• *researcher predicts that there will be a difference between 2 groups but is unable to predict which group will score higher than the other
• There will be a difference between hearing aid and control groups in social anxiety scores
• a hypothesis where we have not specified the direction of the predicted difference or relations

• States the direction of the difference or relationship
• ie. the hearing aid group will have lower social anxiety than the control group
• specified direction of the hypothesis.

Information needed in planning research • Alpha • Effect size • Power • Sample size