What is the difference between a one-tailed and two-tailed hypothesis?
One-tailed
Details the direction of the results (i.e. caffine will increase attention span).
Two-tailed
States there will be an effect but does not predict in which direction (i.e. caffine will affect attention span).
What type of error occurs when we incorrectly reject a null hypothesis?
Type 1
What is the standard error?
The standard deviation of the sampling deviation of the mean.
What is the name of the range of values within which a population mean is likely to fall?
Confidence interval
Give the names of three types of non-normal distributions (with reference to histograms).
Positively skewed
There is a greater range of values higher than the mean. So on a histogram the 'long tail' will be to the right.
Negatively skewed
There is a greater range of values less than the mean . So on a histogram the 'long tail' will be to the left.
Bimodal distribution
Distribution is characterised by two modes. Diagrammatically this would include two bell shaped curves.
What is the more technical term for a key (on a graph)?
Legend
What is an error bar chart?
A bar chart whereby the mean value is represented by a single point and the confidence interval is illustrated by teo lines above and below the point.
What is the accepted measure of dispersion?
Standard Deviation
What is the word used to refer to a whole number?
Integer
What are the three types of variable?
Continuous
Discrete
Categorical
What is a hypothesis?
A statement predicting the result of an experiment.
What type of error would occur if we incorrectly accepted a null hypothesis?
Type 2 error
What type of chart is best used to illustrate frequency?
Histogram
What concept is used when estimating standard deviations for the population from a sample?
Degrees of freedom
What is a null hypothesis?
The null hypothesis will either state that the DV is not dependent on the IV or there is no correlation between two variables, instead any variation is due to sampling error. The purpose of an experiment is to reject the null hypothesis.
What are the four levels of data measurement?
Nominal
Ordinal
Ratio
Interval
What are mean, median and mode referred to as?
Measures of central tendency
What is the value of the degree of freedom when estimating the standard deviation for the population from a sample?
N (number) - 1
What is a double blind experiment?
When the participant and interviewer are both unaware of which condition involves the placebo (e.g. especially in drug trials).
Define the concept of sampling error.
The difference between the values of a sample and those of the whole population (of which the sample was drawn).
What can you do to limit sampling error?
Increase the sample size.
The confidence interval is referred to as what % of accuracy/confidence? This percentage illustrates that given normal distribution ...% of values will fall within how many standard deviation points away from the mean?