Chapter 5 Flashcards
What are the two main purposes of statistical procedures?
1) Describing the results of a study.
2) Helping us understand the meaning of those results
Without statistics, what would we gain from studies?
Very little.
Are statistical procedures and research design closely related?
Yes
Will two individuals respond in exactly the same manner?
No two individuals will respond in exactly the same manner and statistical procedures depend on variability between participants.
What does the variation between each person show?
Individual differences
What descriptive and inferential statistics provide?
Organisation.
What do descriptive statistics do?
Descriptive statistics summarise, simplify and describe such large sets of measurements.
What do inferential statistics do?
Inferential statistics help us interept what the data means.
What does statistcial simplication involve?
Stastical simplication involves computing frequencies.
What is frequency?
Frequency is the number of participants that fall into each category.
What do we arrange frequencies into?
Frequency distributions.
What do frequency distributions show>
Frequency distributions show the frequency in each category.
What is cross tabulation useful for?
Cross tabulation is a useful way to categorise participants based on more them one variable at the same time.
What can cross tabulation help with?
Cross tabulation can help the researcher see relationships between nominal measures.
What is the easiest way to represent score data?
The simplest way to organise a set of score data is to create a frequency distribution.
What does group frequency distribution do?
A group frequency distribution reduces the table to a more manageable size by grouping the scores into intervals.
When is group frequency distribution required?
A grouped frequency distribution is required with a continuous variable in which there are treoretically infinite number of possible scores.
What can graphs do?
Graphs can clarify a data set by presenting the data visually.
What do most people find easier to understand than statistical procedures?
No
What are excellent supplements to statistical analyses?
Graphs and tables.
How are the two ways we can represent frequency of grouped frequency distribution?
Historgram and frequency polygon.
What do both histograms and frequency polygon do?
Represent data on a two-dimensional graph.
What is the x axis also called?
The abscissa
What does the x axis represent?
This represents the range of scores of the variable.
What is the y axis also called?
The ordinate.
What does the y axis represent?
The Y axis represents the frequency of the score.
What is the common shape for systematic distribution?
Bell shaped curve.
What is a bell shaped curve?
This is where most of the participants are near the middle of the distributions and the right and left sides are mirror images.
What are skewed dostributions?
Skewed distributions are where the score piles up on each end of the distrubutions.
What does the tail of the curve represent in skewed distributions?
The tail of the curve indicates the direction of the skew.
What is the central tendency of distribution?
The central tendency of distribution is the location of the middle of distribution on the x axis.
What are the two purposes of descriptive statistics?
These serve two purposes:
1) The first is to describe data with just one or two numbers which makes it easier to compare groups.
2) The second is to provide a basis for later analyses using inferiential statistics.
What are measures of central tendency?
Measures of central tendency describe the typical or average scores.
What do measures of central tendency indicate?
Measures of central tendency indicate the centre of distribution.
What is the centre of distribution?
The centre of distribution is where most of the scores cluster.
What are the three measures of central tendency?
1) Mode
2) Median
3) Mean
What is the mode?
The mode is the most frequently occurring score in the distribution.
Can a distribution have more than one mode?
Yes
What is it causes when there are more then one modes?
If there are two modes it is bimodal.
What is it caused when there are three modes?
If there are three modes it is trimodal.
What is the advantage of a mode?
A distribution may have more than one mode.The mode has the advantage of being easy to compute.
What is the disadvantage of a mode?
.The disadvantage of the mode is that it is unstable and it can be changed with only a few scores.
What is the median?
The median is the middle score in a distribution.
What is the mean?
The mean is the arithemetic average of scores in a distribution.
How is the mean computer?
The mean is computer by summing the scores and dividing the number of scores.
How can we use the mode?
With all scales of measurement.
What is the range?
Range is the distance from the lowest to the highest score in a distribution.
What is the range specified by either?
It may be specified by either giving both the lowest and highest scores or by subtracting the lowest from the highest score and reporting this value.
What is average deviation variance?
Average deviation variance is the arithmetic average of the distance that each score is from the mean.
What is variance?
Variance is essentially the average squared distance from the mean.
What is the variance is computed?
The variance is computed by summing the squared distances from the mean and dividing by the degrees of freedom.
Wat is the degree of freedom?
The degrees of freedom is the sum of scores minus 1.
What is a standard deviation?
Standard deviation is the square root of the variance.
What is the best way to mquantify the relationship between two variables?
The best way to index the relationship between variables is with a correlation coefficient.
What is regression?
Regression refers to the prediction of the value of one variable from the value of another.
What is a standard score?
The standard score is a transformation frequently used in research. The standard score is a relative score because it tells how a participant scored relative to the rest of the participant.
How should ethical researchers use statistics?
Ethical researchers should always use statistics to represent their results accurately and fairly.
What is the effect size?
The effect size is an index of the size of the difference between groups means experessed in standard deviation units.
What does the size of an effect tell us?
It tells us the size of the effect, which indicates how much the indepdent variable shifted the distribution of the dependent variable.
What does power analysis determine?
A power analysis determines how large a sample size should be to detect an existing group difference.
Why is power analysis important?
It is important because it assures that the researcher has sufficient power before the study is started.
What is sampling error?
Sampling error is the normal distribution among different samples of the same population.
Is sampling error a mistake?
It is not a mistake.
What does probability provide?
Probability provides a numerical indication of how likely it is that a given event, as predicted by our findings, will occur.
What does a null hypothesis state?
The null hypothesis states that there is no statistical difference between the population means. If the observed sample means were very different, we would reject the null hypothesis.
